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 https://github.com/microsoft/win32metadata/pull/1620 to improve this. CsWin32 probably just has to leverage it.

[AArnott]

Reactivating because there is lots to fix.