feat: Support lc_collate and lc_ctype session config

[jetjinser]

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What's changed and what's your intention?

For pgAdmin #11048 and tableau #10459

As of now, lc_collate and lc_ctype can always be shown as C but not set.
I'm not sure yet if this locale setting can actually be implemented.

see: https://www.postgresql.org/docs/current/sql-show.html:

• LC_COLLATE Shows the database's locale setting for collation (text ordering).
• LC_CTYPE Shows the database's locale setting for character classification.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
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Documentation

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Release note

Should we wait for the refactoring #10697 to complete first?