AMDGPU: Convert test cases to the dimension-aware intrinsics

Summary:
Also explicitly port over some tests in llvm.amdgcn.image.* that were
missing. Some tests are removed because they no longer apply (i.e.
explicitly testing building an address vector via insertelement).

This is in preparation for the eventual removal of the old-style
intrinsics.

Some additional notes:
- constant-address-space-32bit.ll: change some GCN-NEXT to GCN because
  the instruction schedule was subtly altered
- insert_vector_elt.ll: the old test didn't actually test anything,
  because %tmp1 was not used; remove the load, because it doesn't work
  (Because of the amdgpu_ps calling convention? In any case, it's
  orthogonal to what the test claims to be testing.)

Change-Id: Idfa99b6512ad139e755e82b8b89548ab08f0afcf

Reviewers: arsenm, rampitec

Subscribers: MatzeB, qcolombet, kzhuravl, wdng, yaxunl, dstuttard, tpr, t-tye, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D48018

llvm-svn: 335229