Improve bit fields support

[Nuklon]

Actual behavior

This for example:
https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/d3dkmthk/ns-d3dkmthk-_d3dkmt_adaptertype

is generated as:

		[global::System.CodeDom.Compiler.GeneratedCode("Microsoft.Windows.CsWin32", "0.3.18-beta+dc807e7787")]
		internal partial struct D3DKMT_ADAPTERTYPE
		{
			internal _Anonymous_e__Union Anonymous;

			[StructLayout(LayoutKind.Explicit)]
			[global::System.CodeDom.Compiler.GeneratedCode("Microsoft.Windows.CsWin32", "0.3.18-beta+dc807e7787")]
			internal partial struct _Anonymous_e__Union
			{
				[FieldOffset(0)]
				internal _Anonymous_e__Struct Anonymous;

				[FieldOffset(0)]
				internal uint Value;

				[global::System.CodeDom.Compiler.GeneratedCode("Microsoft.Windows.CsWin32", "0.3.18-beta+dc807e7787")]
				internal partial struct _Anonymous_e__Struct
				{
					internal uint _bitfield;
				}
			}
		}

Expected behavior

Generate helpers around Value for RenderSupported, DisplaySupported, etc.

Repro steps

1. NativeMethods.txt content:

D3DKMT_ADAPTERTYPE

Context

• CsWin32 version: 0.3.18-beta+dc807e7787
• Target Framework: net 6.0
• LangVersion (if explicitly set by project): latest

[AArnott]

It looks like @mikebattista recently did work in microsoft/win32metadata#1620 to improve this. CsWin32 probably just has to leverage it.

[AArnott]

Reactivating because there is lots to fix.