Update ARM feature and CPU detection
* Clean up old LLVM version check
* Clean up old cores that'll probably not be used (and some that are removed from LLVM)
* Add document about data sources
* Update AArch64 feature list to match changes to the LLVM ones
* ARMv8.4 - ARMv8.6 support
* Add all known cores that I can find and all information I can find about them
* Remove a few A64 only cores from AArch32 CPU list
* Rename Apple cores (following LLVM)
* SVE register size
Co-authored-by: Ian <i.r.butterworth@gmail.com>
(cherry picked from commit e0e382515ea3d72fd770781578002f9f8fd80661)
