[clang] Add Clang attribute to ensure that fields are initialized explicitly (PR #102040)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

> I don't think the rfc has reached its conclusion yet, and consensus has not been called (for example, i still need to think about whether my questions were addressed) so we should wait for the RFC process before continuing with that PR.
> 
> Thanks

Thanks for explicitly calling this out. There were no replies from you on the RFC for some time, so it was unclear whether there is anything left. We will be waiting for your feedback on Discourse.

https://github.com/llvm/llvm-project/pull/102040