[llvm] [CHERI] Add enum values and LL parse/print support for CHERI calling conventions. (PR #156328)

[Owen Anderson via llvm-commits]

resistor wrote:

Per communication with @davidchisnall I have corrected a misspelling in one of the CC names. This has already been fixed in the CHERIoT downstream as well. You can find the change here if you would like to apply to it other CHERI-enabled LLVM downstream: https://github.com/CHERIoT-Platform/llvm-project/commit/86c822289fe1bf7b17d78a80cb45d3c937da8646#diff-312583cccc22b4a5264f77751f2d3aef55fc9b9508c861fc81ea448590e9bf46

https://github.com/llvm/llvm-project/pull/156328