DIP: add Bit Fields

[Dennis]

On Saturday, 9 March 2024 at 07:51:08 UTC, Walter Bright wrote:
> The problem with implementation-defined layout is much more of 
> a pedantic one than a pragmatic one, as I've explained 
> elsewhere in this thread.

I've shown that it's a problem when using bit bitfields in D's 
very own standard library (std.internal.unicode_tables) and asked 
you to name one dub package that would benefit from D bit fields 
having C layout, which you didn't do.