[AArch64][SVE] Implement sdot and udot (lane) intrinsics

Summary:
Implements the following arithmetic intrinsics:
  - int_aarch64_sve_sdot
  - int_aarch64_sve_sdot_lane
  - int_aarch64_sve_udot
  - int_aarch64_sve_udot_lane

This patch includes tests for the Subdivide4Argument type added by D67549

Reviewers: sdesmalen, SjoerdMeijer, greened, rengolin, rovka

Reviewed By: sdesmalen

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

Differential Revision: https://reviews.llvm.org/D67551

llvm-svn: 374566