Add/update AssemblyBuilder/PersistedAssemblyBuilder tests covering boundary / edge case scenarios

[buyaa-n]

It was considered useful to add tests for the following cases:

• Test for special characters in member and class names. ECMA-335 doesn't provide rules here, unlike C# for example, but we should check for special characters and strings such as "*", "!", "@", "_", "__", "0x42", "\42" (Unicode escaping), and embedded quotes and nulls. We shouldn't have cases where the input is valid, but the encoding of that fails or is misrepresented.
• Tests for high length counts in member and class names. ECMA-335 doesn't provide rules here, unlike C# for example, but we should verify that long names work as expected.
• Test for class and member name collisions; adding the same property more than once for example.
• Validate ECMA-335 "II.24.2.6 #~ stream" cases when it switches from a 2 byte index to a 4 byte index (65536 methods for example). See also Compiler can silently generate a bad image when there's 0xFFFF parameters in the module #94892

Fixes #103086

[buyaa-n]

Existing AssemblyBuilder adds void type for null return type when populating the signature, now this scenario causing NRE in the SignatureHelper, I could fix it in the signature only, but to avoid NRE's for other case setting the return type to void here.

[AaronRobinsonMSFT]

The constructor parameter, Type returnType isn't marked as nullable. If a null value is sneaking through, we should fix that or mark the parameter as nullable.

[buyaa-n]

Yes, allowing null might was not intentional, but making it throw for null now probably will be breaking change. We might also want to move the null handling from SignatureHelper to RuntimePropertyBuilder

runtime/src/coreclr/System.Private.CoreLib/src/System/Reflection/Emit/SignatureHelper.cs

Lines 144 to 150 in 9fe8c95

	public static SignatureHelper GetPropertySigHelper(Module? mod, CallingConventions callingConvention,
	Type? returnType, Type[]? requiredReturnTypeCustomModifiers, Type[]? optionalReturnTypeCustomModifiers,
	Type[]? parameterTypes, Type[][]? requiredParameterTypeCustomModifiers, Type[][]? optionalParameterTypeCustomModifiers)
	{
	SignatureHelper sigHelp;
	returnType ??= typeof(void);

[AaronRobinsonMSFT]

Sure, that makes sense. I don't think we should throw either, but I do like to have the nullable indicators correct so we can check these things.

[buyaa-n]

Done

[steveharter]

Existing AssemblyBuilder adds void type for null return type when populating the signature,

I assume this behavior exists in previous versions as well?

[buyaa-n]

Yes, RuntimePropertyBuilder constructor was allowing null, but not handling null which could cause NRE further if SetConstant called for the property, the null has been resolved only for GetPropertySigHelper. I see same behavior in .NET framework.

Now with this PR the null return type will be handled to void type in the RuntimePropertyBuilder constructor, same as in GetPropertySigHelper.

[steveharter]

Some misc questions, but otherwise LGTM

[steveharter]

Buyaa out, merged.