[MLIR][Affine] Add utility to check if the slice is valid
Fixes a bug in affine fusion pipeline where an incorrect slice is computed.
After the slice computation is done, original domain of the the source is
compared with the new domain that will result if the fusion succeeds. If the
new domain must be a subset of the original domain for the slice to be
valid. If the slice computed is incorrect, fusion based on such a slice is
Relevant test cases are added/edited.
Differential Revision: https://reviews.llvm.org/D98239