[PowerPC] Add -m[no-]power10-vector clang and llvm option

Summary: This patch adds command line option for enabling power10-vector support.

Reviewers: hfinkel, nemanjai, lei, amyk, #powerpc

Reviewed By: lei, amyk, #powerpc

Subscribers: wuzish, kbarton, hiraditya, shchenz, cfe-commits, llvm-commits

Tags: #llvm, #clang, #powerpc

Differential Revision: https://reviews.llvm.org/D80758