[Mono.Android] Use the faster java type name mapping (#1890)

Fixes: #1831

Make sure we use the code path, which uses the `typename.*` maps.
It is much faster than `JavaNativeTypeManager.ToJniName()`.

Tested with x86 emulator again. It saves 17ms (from 18ms to 1ms) in
XA template and 26ms (from 28ms to 2ms) in XamlSamples app.

This change also decreases JIT usage: in the XA template app,
*Compiled methods* is reduced from 1954 to 1880 methods.

src/Mono.Android/Java.Interop/TypeManager.cs

@@ -309,7 +309,7 @@ internal static object CreateProxy (Type type, IntPtr handle, JniHandleOwnership
 
 		public static void RegisterType (string java_class, Type t)
 		{
-			string jniFromType = JavaNativeTypeManager.ToJniName (t);
+			string jniFromType = JNIEnv.GetJniName (t);
 			lock (jniToManaged) {
 				Type lookup;
 				if (!jniToManaged.TryGetValue (java_class, out lookup)) {