[mlir][IR] Add listener notifications for pattern begin/end (#84131)

This commit adds two new notifications to `RewriterBase::Listener`:
* `notifyPatternBegin`: Called when a pattern application begins during
a greedy pattern rewrite or dialect conversion.
* `notifyPatternEnd`: Called when a pattern application finishes during
a greedy pattern rewrite or dialect conversion.

The listener infrastructure already provides a `notifyMatchFailure`
callback that notifies about the reason for a pattern match failure. The
two new notifications provide additional information about pattern
applications.

This change is in preparation of improving the handle update mechanism
in the `apply_conversion_patterns` transform op.