[AArch64][SVE] Add permutation and selection intrinsics

Summary:
Adds the following intrinsics:

    * @llvm.aarch64.sve.clasta
    * @llvm.aarch64.sve.clasta_n
    * @llvm.aarch64.sve.clastb
    * @llvm.aarch64.sve.clastb_n
    * @llvm.aarch64.sve.compact
    * @llvm.aarch64.sve.ext
    * @llvm.aarch64.sve.lasta
    * @llvm.aarch64.sve.lastb
    * @llvm.aarch64.sve.rev
    * @llvm.aarch64.sve.splice
    * @llvm.aarch64.sve.tbl
    * @llvm.aarch64.sve.trn1
    * @llvm.aarch64.sve.trn2
    * @llvm.aarch64.sve.uzp1
    * @llvm.aarch64.sve.uzp2
    * @llvm.aarch64.sve.zip1
    * @llvm.aarch64.sve.zip2

Reviewers: sdesmalen, efriedma, dancgr, mgudim, huntergr, rengolin

Reviewed By: sdesmalen, efriedma

Subscribers: kmclaughlin, tschuett, kristof.beyls, hiraditya, rkruppe, psnobl, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71401