L025: Derived query requires alias -- also handle UNION, etc.

[barrywhart]

Brief summary of the change made

Fixes #3547
This is a one-line change to yesterday's PR (#3546)

Are there any other side effects of this change that we should be aware of?

Pull Request checklist

• Please confirm you have completed any of the necessary steps below.

• Included test cases to demonstrate any code changes, which may be one or more of the following:

  • .yml rule test cases in test/fixtures/rules/std_rule_cases.
  • .sql/.yml parser test cases in test/fixtures/dialects (note YML files can be auto generated with tox -e generate-fixture-yml).
  • Full autofix test cases in test/fixtures/linter/autofix.
  • Other.

• Added appropriate documentation for the change.

• Created GitHub issues for any relevant followup/future enhancements if appropriate.

[codecov]

Codecov Report

Merging #3548 (3fc82ec) into main (fe8b93e) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main     #3548   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          172       172           
  Lines        13064     13064           
=========================================
  Hits         13064     13064           

Impacted Files	Coverage Δ
src/sqlfluff/rules/L025.py	100.00% <ø> (ø)

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[tunetheweb]

Approved. Could you do me a favour though and search the rules for set_expression? I’ve a funny feeling another rules uses that with select_expression and one other too which we might want to add here.

[barrywhart]

Will do. It'll probably be this afternoon. I'm about to go somewhere with the family.

[tunetheweb]

Maybe just merge this in meantime then?

[barrywhart]

@tunetheweb: Good catch! The other case is with_compound_statement. I added a test case and a fix for that too. Once the build passes, I'll merge this and make the release.