Enable duplication checks by default

[majosm]

Duplication checks have been off by default due to some subpackages still having code that duplicates. Now that inducer/arraycontext#221 has been merged, it may be possible to enable the checks by default. Likely there are still a few spots in arraycontext/meshmode/grudge (and the production versions of those) that need fixing, but hopefully they should be minor.

Draft because:

• Requires Deduplicate in _dag_to_compiled_func arraycontext#324 and Avoid duplication in PytatoJAXArrayContext.freeze arraycontext#325
• Requires Avoid duplication in untag_loopy_call_results meshmode#467
• Requires Deduplicate in _dag_to_compiled_func grudge#384
• Merge meshmode production changes

[inducer]

#616 should clean up some of the bpr nonsense.

[majosm]

Note to self: These should probably be err_on_<whatever>=__debug__ rather than err_on_<whatever>=True.

[majosm]

@inducer I looked into what specifically was making the mapper-created duplicate check in Deduplicator slow. Seems it's because the EqualityComparer cache isn't preserved across the different rec calls in Deduplicator. I attempted a fix here. Confirmed that it works in illinois-ceesd/drivers_y3-prediction#91. Thoughts?

I also took a stab at caching equality for mapper cache dict lookups here, but at least with my implementation it didn't show any benefit (number of equality rec calls went down a few percent, but overall time actually got a little worse).

[inducer]

LGTM subject to:

• Let's defer sorted removal until we're on constantdict