[MLIR][FlatAffineConstraints] Add support for extracting divisions with tighter bounds

[MLIR][FlatAffineConstraints] Add support for extracting divisions with tighter bounds

This patch adds support for extracting divisions when the set contains bounds
which are tighter than the division bounds. For example:

```
     3q - i + 2 >= 0                       <-- Lower bound for 'q'
    -3q + i - 1 >= 0                       <-- Tighter upper bound for 'q'
```

Here, the actual upper bound for division for `q` would be `-3q + i >= 0`, but
since this actual upper bound is implied by a tighter upper bound, which awe can still
extract the divison.

Reviewed By: arjunp

Differential Revision: https://reviews.llvm.org/D115096