chore: Embrace the walrus operator

[john-bodley]

SUMMARY

In #23890 (thanks to @sebastianliebscher) we dropped support for Python 3.8 and thus now we are free to embrace the walrus (:=) operator. This PR adds a pre-commit hook (which runs before black) to ensure we never have code of the form,

 n = 10
 if n > 3:
     print(n)

but rather,

if (n := 10) > 3:
    print(n)

Note the pre-commit hook only detects/remedies simple use cases. Personally I've found the walrus operator really handy in list comprehensions (when you need to assign a temporary variable) and logic like,

foo = bar()
return foo.value if foo else None

which becomes,

return foo.value if (foo := bar()) else None

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

CI.

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #24127 (f15554e) into master (2222073) will decrease coverage by 0.04%.
The diff coverage is 64.40%.

❗ Current head f15554e differs from pull request most recent head ed4e4c8. Consider uploading reports for the commit ed4e4c8 to get more accurate results

@@            Coverage Diff             @@
##           master   #24127      +/-   ##
==========================================
- Coverage   68.30%   68.26%   -0.04%     
==========================================
  Files        1952     1952              
  Lines       75432    75388      -44     
  Branches     8191     8202      +11     
==========================================
- Hits        51521    51462      -59     
- Misses      21807    21819      +12     
- Partials     2104     2107       +3     

Flag	Coverage Δ
hive	53.23% <23.75%> (+0.06%)	⬆️
mysql	78.94% <80.00%> (-0.01%)	⬇️
postgres	79.01% <80.00%> (-0.01%)	⬇️
presto	53.16% <25.00%> (+0.06%)	⬆️
python	82.81% <83.75%> (-0.01%)	⬇️
sqlite	77.54% <77.50%> (+<0.01%)	⬆️
unit	53.18% <12.50%> (+0.08%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...set-ui-core/src/ui-overrides/ExtensionsRegistry.ts	100.00% <ø> (ø)
...et-frontend/src/components/TableSelector/index.tsx	81.08% <ø> (ø)
...end/src/features/databases/DatabaseModal/styles.ts	77.66% <ø> (ø)
superset-frontend/src/pages/DatabaseList/index.tsx	66.03% <0.00%> (ø)
superset/datasets/commands/importers/v1/utils.py	79.41% <0.00%> (+0.77%)	⬆️
superset/db_engine_specs/databricks.py	70.92% <0.00%> (+0.49%)	⬆️
superset/db_engine_specs/snowflake.py	67.64% <0.00%> (+0.39%)	⬆️
superset/migrations/env.py	0.00% <0.00%> (ø)
superset/models/helpers.py	69.90% <0.00%> (+0.07%)	⬆️
superset/views/api.py	68.75% <0.00%> (+1.05%)	⬆️
... and 45 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[john-bodley]

Sadly we're stuck between a rock and a hard place here. There is a Pylint false positive on line #265 but if we add the disable comment there then Black will reformat the line because its > 88 characters and the formatting then requires the extra (...) per Pylint's rules.

[john-bodley]

Probably should reformat the code before running Mypy, Black, etc.

[villebro]

Lol, love the auto walrus! Btw walrus was already added in 3.8, so it's been supported on the codebase for quite some time (3.7 was deprecated here in March 2022: #19017)

[villebro]

I browsed through all the changes, and they LGTM. Happy to see this enforced, as I'm also a big fan of the walrus.