[MLIR][Presburger] Merge PresburgerLocalSpace and PresburgerSpace

This patch is a cleanup patch that merges PresburgerLocalSpace and
PresburgerSpace. Asserting that there are no locals is shifted to the
users of PresburgerSpace themselves.

The reasoning for this patch is that PresburgerLocalSpace did not contribute
much and only introduced additional complexity as locals could still be present
in PresburgerSpace, just not writable. This could introduce problems if a
PresburgerSpace with locals was copied to PresburgerLocalSpace which expected
no locals in a PresburgerSpace.

Reviewed By: arjunp

Differential Revision: https://reviews.llvm.org/D122353