[mlir][Interfaces] `ValueBoundsOpInterface`: Add API to compare values (#86915)

This commit adds a new public API to `ValueBoundsOpInterface` to compare
values/dims. Supported comparison operators are: LT, LE, EQ, GE, GT.

The new `ValueBoundsOpInterface::compare` API replaces and generalizes
`ValueBoundsOpInterface::areEqual`. Not only does it provide additional
comparison operators, it also works in cases where the difference
between the two values/dims is non-constant. The previous implementation
of `areEqual` used to compute a constant bound of `val1 - val2` (check
if it `== 0` or `!= 0`).

Note: This commit refactors, generalizes and adds a public API for
value/dim comparison. The comparison functionality itself was introduced
in #85895 and is already in use for analyzing `scf.if`.

In the long term, this improvement will allow for a more powerful
analysis of subset ops. A future commit will update
`areOverlappingSlices` to use the new comparison API.
(`areEquivalentSlices` is already using the new API.) This will improve
subset equivalence/disjointness checks with non-constant
offsets/sizes/strides.