Clang SME ACLE intrinsics

In our downstream compiler, we have previously implemented some custom C intrinsics for ARM Scalable Matrix Extension. Since ARM posted the ACLE draft for SME ([main] Add Alpha support for SME by rsandifo-arm · Pull Request #188 · ARM-software/acle · GitHub), we have started refactoring our implementation to support ACLE instead. The first patch has been posted on Phabricator (⚙ D127910 [Clang][AArch64] Add SME C intrinsics for load and store). I would appreciate it if you could review and give us some feedback. We would love to contribute more to the effort if this is the right direction.