Fix parameters for Snowflake create tasks statement

[chwiese]

Brief summary of the change made

Fixes options for the CREATE TASK statement in the Snowflake dialect:

• One can only specify the WAREHOUSE parameter or the USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE parameter, but not both
• The parameters can be in arbitrary order, except for AFTER which must be last
• The value for USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE is a warehouse size, not a quoted literal. Warehouse sizes themselves are not identifiers, so I am changing the type of that RegexParser.
• The quotes around the warehouse sizes are optional, except for the ones with hyphens, which must be quoted. The same rules apply the CREATE WAREHOUSE statements, even if that is not clearly documented there.

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

None.

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 python test/generate_parse_fixture_yml.py or by running tox locally).
  • 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 #2037 (2b886dc) into main (0f8d2c1) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main     #2037   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          148       148           
  Lines        10495     10495           
=========================================
  Hits         10495     10495           

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

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[jpy-git]

@chwiese very small tweak to remove the unnecessary default delimiter, but otherwise perfect and will approve and merge after once that line is removed ⭐

[jpy-git]

LGTM, well done @chwiese 🚀 🌟