Fixes: dotnet#5652

Each trimming problem listed below.

~~ AndroidEnvironment ~~

    src\Mono.Android\Android.Runtime\AndroidEnvironment.cs(373,19): error IL2057: Unrecognized value passed to the parameter 'typeName' of method 'System.Type.GetType(String, Boolean)'. It's not possible to guarantee the availability of the target type.
    src\Mono.Android\Android.Runtime\AndroidEnvironment.cs(379,22): error IL2057: Unrecognized value passed to the parameter 'typeName' of method 'System.Type.GetType(String, Boolean)'. It's not possible to guarantee the availability of the target type.
    src\Mono.Android\Android.Runtime\AndroidEnvironment.cs(342,20): error IL2057: Unrecognized value passed to the parameter 'typeName' of method 'System.Type.GetType(String, Boolean)'. It's not possible to guarantee the availability of the target type.
    src\Mono.Android\Android.Runtime\AndroidEnvironment.cs(352,11): error IL2077: 'type' argument does not satisfy 'DynamicallyAccessedMemberTypes.PublicParameterlessConstructor' in call to 'System.Activator.CreateInstance(Type)'. The field 'Android.Runtime.AndroidEnvironment.httpMessageHandlerType' does not have matching annotations. The source value must declare at least the same requirements as those declared on the target location it is assigned to.

To fix these:

* Use constant strings for calls like:

    Type.GetType ("System.Net.Http.HttpMessageHandler, System.Net.Http", throwOnError: false)

Use `Type.IsAssignableFrom()` inline, and the trimmer now understands
the code paths.

There is a problem here if either of these are used with a custom type:

* `$(AndroidHttpClientHandlerType)`
* `$XA_HTTP_CLIENT_HANDLER_TYPE`

This is a rarely used feature, I found one usage in GitHub:

https://github.com/search?q=%3CAndroidHttpClientHandlerType%3E+NOT+Xamarin.Android.Net+NOT+System.Net.Http+NOT+Default&type=code

Filed an issue to fix this in the future:

* dotnet#8797

~~ JavaConvert ~~

    src\Mono.Android\Java.Interop\JavaConvert.cs(223,12): error IL2091: 'TResult' generic argument does not satisfy 'DynamicallyAccessedMemberTypes.PublicConstructors', 'DynamicallyAccessedMemberTypes.NonPublicConstructors' in 'Java.Interop.JavaObjectExtensions._JavaCast<TResult>(IJavaObject)'. The generic parameter 'T' of 'Java.Interop.JavaConvert.FromJavaObject<T>(IJavaObject, out Boolean)' does not have matching annotations. The source value must declare at least the same requirements as those declared on the target location it is assigned to.
    src\Mono.Android\Java.Interop\JavaConvert.cs(254,12): error IL2067: 'resultType' argument does not satisfy 'DynamicallyAccessedMemberTypes.PublicConstructors', 'DynamicallyAccessedMemberTypes.NonPublicConstructors' in call to 'Java.Interop.JavaObjectExtensions.JavaCast(IJavaObject, Type)'. The parameter 'targetType' of method 'Java.Interop.JavaConvert.FromJavaObject(IJavaObject, Type)' does not have matching annotations. The source value must declare at least the same requirements as those declared on the target location it is assigned to.
    src\Mono.Android\Java.Interop\JavaConvert.cs(67,14): error IL3050: Using member 'System.Type.MakeGenericType(params Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.
    src\Mono.Android\Java.Interop\JavaConvert.cs(73,14): error IL3050: Using member 'System.Type.MakeGenericType(params Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.
    src\Mono.Android\Java.Interop\JavaConvert.cs(79,14): error IL3050: Using member 'System.Type.MakeGenericType(params Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.

Adding attributes fixed some of these.

I suppressed warnings for:

* `Type.MakeGenericType()`: `JavaDictionary<,>`, `JavaList<>`, and
  `JavaCollection<>` use DynamicDependency to preserve `FromJniHandle`
  method.

* `Type.GetElementType()`: for calling `MyJavaObject[]` constructors,
  the `MarkJavaObjects` trimmer step should preserve these
  constructors.

This trickled over to require more attributes for:

* `AdapterView`
* `ArrayAdapter`
* `AsyncTask`
* `JavaCollection`
* `JavaDictionary`
* `JavaList`
* `JavaList`
* `JavaObjectExtensions`
* `JavaSet`
* `SparseArray`
* `System.Linq\Extensions`

~~ JNIEnv ~~

    src\Mono.Android\Android.Runtime\JNIEnv.cs(810,38): error IL3050: Using member 'System.Type.MakeArrayType()' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The code for an array of the specified type might not be available.
    src\Mono.Android\Android.Runtime\JNIEnv.cs(953,33): error IL3050: Using member 'System.Type.MakeArrayType()' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The code for an array of the specified type might not be available.
    src\Mono.Android\Android.Runtime\JNIEnv.cs(1078,44): error IL3050: Using member 'System.Type.MakeArrayType()' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The code for an array of the specified type might not be available.
    src\Mono.Android\Android.Runtime\JNIEnv.cs(1139,15): error IL2091: 'T' generic argument does not satisfy 'DynamicallyAccessedMemberTypes.PublicConstructors', 'DynamicallyAccessedMemberTypes.NonPublicConstructors' in 'Java.Interop.JavaConvert.FromJavaObject<T>(IJavaObject)'. The generic parameter 'T' of 'Android.Runtime.JNIEnv.GetArray<T>(Object[])' does not have matching annotations. The source value must declare at least the same requirements as those declared on the target location it is assigned to.
    src\Mono.Android\Android.Runtime\JNIEnv.cs(1060,14): error IL3050: Using member 'System.Array.CreateInstance(Type, Int32)' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The code for an array of the specified type might not be available.
    src\Mono.Android\Android.Runtime\JNIEnv.cs(1065,14): error IL3050: Using member 'System.Array.CreateInstance(Type, Int32)' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The code for an array of the specified type might not be available.
    src\Mono.Android\Android.Runtime\JNIEnv.cs(1257,23): error IL2091: 'T' generic argument does not satisfy 'DynamicallyAccessedMemberTypes.PublicConstructors', 'DynamicallyAccessedMemberTypes.NonPublicConstructors' in 'Java.Interop.JavaConvert.FromJniHandle<T>(nint, JniHandleOwnership)'. The generic parameter 'T' of 'Android.Runtime.JNIEnv.CopyObjectArray<T>(nint, T[])' does not have matching annotations. The source value must declare at least the same requirements as those declared on the target location it is assigned to.

Adding some attributes fixed two of these.

Suppress NativeAOT warnings, in source, for:

* `Array.CreateInstance()`

* `Type.MakeArrayType()`

Link to an issue to fix in the future.