Define pass to hold `scf` (and other dialects) canonicalization patterns defined in `polygeist`

**Is your feature request related to a problem? Please describe**

Currently, `polygeist` defines some canonicalization patterns for operations defined in other dialects, so, if `polygeist` isn't loaded, these won't be loaded and won't be applied.

**Describe the solution you would like**

We should define a pass instead and apply the patterns that way.

**Describe alternatives you have considered**

Define canonicalization patterns in their respective dialects, but this would make us diverge from upstream.

**Additional context**

This began failing [in this PR](https://github.com/intel/llvm/pull/8692), which exposed this flaw as we got ready for dropping the deprecated feature.