feat(report): add/edit modal improvements

[lilykuang]

SUMMARY

• changed sql field from textarea to TextAreaControl with sql highlight
• added helper text for cron schedule field
• added helper text for notification method

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TEST PLAN

• ui unit test

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[codecov-io]

Codecov Report

Merging #12183 (978d666) into master (a52031a) will decrease coverage by 3.53%.
The diff coverage is 90.90%.

@@            Coverage Diff             @@
##           master   #12183      +/-   ##
==========================================
- Coverage   66.61%   63.08%   -3.54%     
==========================================
  Files         994      994              
  Lines       49079    49074       -5     
  Branches     4982     4983       +1     
==========================================
- Hits        32695    30956    -1739     
- Misses      16254    17918    +1664     
- Partials      130      200      +70     

Flag	Coverage Δ
cypress	?
javascript	61.26% <90.90%> (+0.02%)	⬆️
python	64.25% <ø> (+0.03%)	⬆️

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

Impacted Files	Coverage Δ
...frontend/src/views/CRUD/alert/AlertReportModal.tsx	46.88% <85.71%> (+0.78%)	⬆️
...CRUD/alert/components/AlertReportCronScheduler.tsx	88.46% <100.00%> (+1.50%)	⬆️
superset-frontend/src/explore/App.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/dashboard/App.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/setup/setupColors.js	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/chart/ChartContainer.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/explore/reducers/index.js	0.00% <0.00%> (-100.00%)	⬇️
...et-frontend/src/dashboard/containers/Dashboard.jsx	0.00% <0.00%> (-100.00%)	⬇️
...t-frontend/src/dashboard/containers/SliceAdder.jsx	0.00% <0.00%> (-100.00%)	⬇️
...t-frontend/src/explore/reducers/getInitialState.js	0.00% <0.00%> (-100.00%)	⬇️
... and 175 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update a52031a...01175ed. Read the comment docs.

[nytai]

Code LGTM. I'm wondering if we really need to crontab.guru link, it seems to me that users who are unfamiliar with cron syntax should use the picker and users who want to write cron strings can do so via the input box.