Add CommaSegment to AlterWarehouseStatementSegment SET clause

[moreaupascal56]

Brief summary of the change made

Allow the use of commas (as it is either space or commas) to separate properties of a SET clause in AlterWarehouseStatementSegment
makes progress on #3479

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

no

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.

[coveralls]

coverage: 100.0%. remained the same when pulling 6673788 on moreaupascal56:snowflake-alter-warehouse-allow-commas-in-set-clause into 5680394 on sqlfluff:main.

[github-actions]

Coverage Results ✅

Name    Stmts   Miss  Cover   Missing
-------------------------------------
TOTAL   16731      0   100%

221 files skipped due to complete coverage.

[alanmcruickshank]

Nice! Good catch 👍