Allow global config for rule testcases

[sti0]

Brief summary of the change made

This allows to define a global config (e.g. dialect) per rule test. If a config is defined within a single testcase, this one still respected (behaviour as is).

Example:

rule: R001
configs:
    core:
      dialect: exasol


tc1:
  pass_str: |
    create table if not exists tab.xxx (col1 varchar(10))
  configs:
    core:
      dialect: ansi

tc2:
  pass_str: |
    create table tab.xxx (col1 varchar(10))

tc3:
  pass_str: |
    create or replace table tab.xxx (col1 varchar(10))

While tc1 still uses ansi dialect, tc2 and tc3 are using exasol dialect

...

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/parser (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 #1580 (8290b23) into main (a475335) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##             main     #1580      +/-   ##
===========================================
+ Coverage   99.98%   100.00%   +0.01%     
===========================================
  Files         131       131              
  Lines        9175      9180       +5     
===========================================
+ Hits         9174      9180       +6     
+ Misses          1         0       -1     

Impacted Files	Coverage Δ
src/sqlfluff/testing/rules.py	100.00% <100.00%> (ø)
src/sqlfluff/core/config.py	100.00% <0.00%> (+0.35%)	⬆️

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[alanmcruickshank]

This looks mostly great. I'd love to add a little more explanation around the test case that you've added, but otherwise excellent. Thanks for putting this together 🚀 .

[tunetheweb]

What’s the use case out of interest? Is this more for custom rules?

[sti0]

What’s the use case out of interest? Is this more for custom rules?

Exactly. We only run Exasol database and all of the custom rules should be tested against this dialect.

[tunetheweb]

@alanmcruickshank looks like you need to re-review before this can be merged.