[llvm] [RISCV] Add support for new unprivileged extensions defined in profiles spec (PR #77458)

[Luke Lau via llvm-commits]

lukel97 wrote:

> As RVA22 is ratified, I think treating this as non-experimental and v1.0 (as you have) makes sense. I'm wondering if Ziccrse, Ziccamoa, Za64rs, and Za128rs should imply A though?

Yeah, I just chose 1.0 since I couldn't find any other information on them.
I also considered implying A but I couldn't find any mention of it in the spec. These extensions are all more or less defined by a single sentence. Do we have any existing precedent where we take the liberty of assuming implied extensions?

https://github.com/llvm/llvm-project/pull/77458