fix(explore): checkbox form control formatting

[suddjian]

SUMMARY

Fixes a recently introduced formatting issue.

Also changed the Field to a Typescriptified function component.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Before:

After:

TEST PLAN

On Explore, open up the Edit Dataset modal and go to Settings

ADDITIONAL INFORMATION

• Has associated issue:
• 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 #14701 (c78dd77) into master (2320bd4) will decrease coverage by 0.01%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##           master   #14701      +/-   ##
==========================================
- Coverage   77.55%   77.54%   -0.02%     
==========================================
  Files         958      959       +1     
  Lines       48550    48608      +58     
  Branches     5703     5734      +31     
==========================================
+ Hits        37654    37693      +39     
- Misses      10696    10714      +18     
- Partials      200      201       +1     

Flag	Coverage Δ
javascript	72.51% <81.81%> (-0.02%)	⬇️

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

Impacted Files	Coverage Δ
...erset-frontend/src/datasource/DatasourceEditor.jsx	66.38% <ø> (ø)
superset-frontend/src/CRUD/Field.tsx	80.00% <80.00%> (ø)
superset-frontend/src/components/Form/FormItem.tsx	100.00% <100.00%> (ø)
...erset-frontend/src/SqlLab/components/ResultSet.tsx	67.31% <0.00%> (-2.69%)	⬇️
...nd/src/explore/components/ExploreActionButtons.tsx	71.73% <0.00%> (-0.61%)	⬇️
superset-frontend/src/explore/constants.ts	100.00% <0.00%> (ø)
...erset-frontend/src/SqlLab/components/SqlEditor.jsx	54.62% <0.00%> (ø)
...-frontend/src/SqlLab/components/SouthPane/state.ts	100.00% <0.00%> (ø)
...tend/src/SqlLab/components/SouthPane/SouthPane.tsx	79.54% <0.00%> (ø)
...end/src/dashboard/components/SliceHeader/index.tsx	92.00% <0.00%> (ø)
... and 10 more

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