[clang] [Sema] Add check for bitfield assignments to integral types (PR #69049)

[Paul Kirth via cfe-commits]

ilovepi wrote:

Hi, is there a way to disable this check w/o disabling all `-Wconversion` warnings? We'd like to disable this one on some third_party code(e.g. the vulkansdk), but keep `-Wconversion` as a whole in place whenever we can. Unfortunately, `-Wno-bitfield-conversion` doesn't seem to be accepted, so I'd like some guidance on how to disable this diagnostic without losing the whole category.

https://github.com/llvm/llvm-project/pull/69049