[clang] [llvm] [AArch64] Add optional extensions enabled on Grace (PR #127620)

[Sjoerd Meijer via cfe-commits]

https://github.com/sjoerdmeijer approved this pull request.

LGTM, but worth looking at Dave's suggestion before merging this:

> It currently uses a bit of a mixture of specifying features individually (FeatureAES and FeatureSVEAES) and relying on the dependencies (FeatureSVE2SHA3 will imply FeatureSHA3 but isn't specified directly). It might be good to use one or the other, whichever that is, but It shouldn't alter the result.



https://github.com/llvm/llvm-project/pull/127620