release-22.1: opt: check UDTs by name when checking metadata dependencies

[DrewKimball]

Backport 2/4 commits from #96045.

/cc @cockroachdb/release

---

opt: refactor metadata dependency tracking

This commit performs some refactoring for the way data source objects
are tracked in opt.Metadata in order to make future changes to UDT
and UDF dependency tracking easier. More particularly, UDTs and UDFs
will be able to re-resolve any references by name. This is necessary
in order to handle cases where changes to the search-path cause names
in the query to resolve to different objects.

opt: track UDT references by name in the Metadata

Previously, it was possible for invalid queries to be kept in the cache
after a schema change, since user-defined types were tracked only by OID.
This missed cases where the search path changed which object a name in
the query resolved to (or whether it resolved at all).

This patch fixes this behavior by tracking UDT references by name, similar
to what was already done for data sources. This ensures that the query
staleness check doesn't miss changes to the search path.

Fixes #96674

Release note (bug fix): Fixed a bug that could prevent a cached query from being invalidated when a UDT referenced by that query was altered or dropped, or when the schema or database of a UDT was altered or dropped.

Release Justification: low-risk bug fix for rare incorrect results for UDTs

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues or test-only changes.
• Patches should not break backwards-compatibility.
• Patches should change as little code as possible.
• Patches should not change on-disk formats or node communication protocols.
• Patches should not add new functionality.
• Patches must not add, edit, or otherwise modify cluster versions; or add version gates.

If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters.
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

• What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
• Will this work in a cluster of mixed patch versions? Did we test that?
• If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

[cockroach-teamcity]

This change is 

[mgartner]

LGTM

[DrewKimball]

TFYR!