[AArch64][SVE] Add ptest intrinsics

Summary:
Implements the following intrinsics:

    * @llvm.aarch64.sve.ptest.any
    * @llvm.aarch64.sve.ptest.first
    * @llvm.aarch64.sve.ptest.last

Reviewers: sdesmalen, efriedma, dancgr, mgudim, cameron.mcinally, rengolin

Reviewed By: efriedma

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72398