sql: Keep spaces when using unaccent

[aeekayy]

The previous behavior of unaccent removed spaces, but that is not
compatible with the PG implementation.

Fixes #100407

Release note (bug fix): The unaccent builtin function no longer removes
spaces.

Operation

SELECT unaccent('Héllô Wõrld!');

Expected behavior

Hello World!

Old behavior

HelloWorld!

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[cockroach-teamcity]

This change is 

[rafiss]

thanks for your contribution! i will merge this

[rafiss]

please update your commit message. i tried making this change, but i don't have permission to push to your fork

builtins: update unaccent to leave spaces alone

The previous behavior of unaccent removed spaces, but that is not
compatible with the PG implementation.

Release note (bug fix): The unaccent builtin function no longer removes
spaces.

[rafiss]

the commit message still needs to be updated

[blathers-crl]

Thank you for updating your pull request.

My owl senses detect your PR is good for review. Please keep an eye out for any test failures in CI.

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}

[rafiss]

thank you!

bors r+

[aeekayy]

@rafiss I pushed the updated commit message

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)