[mono] Improve how EnumBuilder handles type attributes

[alexischr]

Literally copy set of attributes from

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

Line 330 in dc62dd6

m_underlyingField = m_typeBuilder.DefineField("value__", underlyingType, FieldAttributes.Public | FieldAttributes.SpecialName | FieldAttributes.RTSpecialName);

, and mask reserved attributes in FieldBuilder

contributes to #2389

[marek-safar]

This should allow you to re-enable some tests, right?

[akoeplinger]

The pending Installer Build and Test Windows_NT_x86 Debug is green on AzDO (looks like the updated status didn't make it to GitHub) so feel free to merge after addressing Marek's question.

[lambdageek]

This should allow you to re-enable some tests, right?

This contributes to #2389 and should allow us to enable S.R.E.Tests.ModuleBuilder.DefineEnum eventually, but right now it will still fail because of the test input that has "a\0b\0c" as the type name.

runtime/src/libraries/System.Reflection.Emit/tests/ModuleBuilder/ModuleBuilderDefineEnum.cs

Lines 19 to 35 in b74422f

	yield return new object[] { "a\0b\0c", TypeAttributes.Public, typeof(int) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(uint) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(long) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(char) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(bool) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(ulong) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(float) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(double) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(IntPtr) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(UIntPtr) };
	yield return new object[] { "Name", TypeAttributes.Public, typeof(Int32Enum) };
	}
	[Theory]
	[ActiveIssue("https://github.com/dotnet/runtime/issues/2389", TestRuntimes.Mono)]
	[MemberData(nameof(DefineEnum_TestData))]
	public void DefineEnum(string name, TypeAttributes visibility, Type underlyingType)