fix: Loading overlay bugfix and cleanup

[rusackas]

SUMMARY

Initial report:

"Filter widgets don't show a ""loading"" spinner, so there is no indication of when the (valid) filter values are loaded. This is a problem with dynamic filters where the underlying logic that returns the filter values can change, or where they depend on settings for other values. The only way to see when it's been updated is by examining the drop-down values to see when they've changed (or if you know what to expect, when the correct values are shown).

Issue uncovered:
The loader was indeed there, but buried (z-index-wise) below the controls.

The fix:
Could this be fixed with one line of CSS? Yep! But that's not the right way. This PR does the following:

1. Reverses the rendering order of the three key layers in chart.jsx so the Loader is atop the Refresh overlay atop the Chart itself. Not sure why it would be the other way, but if anyone has some idea, let me know!

2. Touches up a bunch of CSS to make the positioning of those re-stacked elements work

3. Moves the CSS out of LESS and into Emotion 👩‍🎤

4. Migrates Loading and RefreshChartOverlay components to tsx.

5. Removes the size prop from Loading, which sure seems to be unused

6. Removes some unused css for a "dismiss" button that no longer seems to exist.

BEFORE

AFTER

TEST PLAN

ADDITIONAL INFORMATION

• Has associated issue: Preset SO-553
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[etr2460]

a couple comments, thanks for fixing this!

[etr2460]

a couple comments, thanks for fixing this!

[villebro]

Awesome, works like a charm!

[codecov-commenter]

Codecov Report

Merging #10105 into master will decrease coverage by 0.09%.
The diff coverage is 84.61%.

@@            Coverage Diff             @@
##           master   #10105      +/-   ##
==========================================
- Coverage   70.56%   70.46%   -0.10%     
==========================================
  Files         590      590              
  Lines       31150    31209      +59     
  Branches     3164     3192      +28     
==========================================
+ Hits        21981    21992      +11     
- Misses       9060     9101      +41     
- Partials      109      116       +7     

Flag	Coverage Δ
#cypress	53.44% <88.88%> (-0.39%)	⬇️
#javascript	59.58% <38.46%> (+0.04%)	⬆️
#python	70.19% <ø> (+<0.01%)	⬆️

Impacted Files	Coverage Δ
...et-frontend/src/SqlLab/components/TableElement.jsx	82.75% <0.00%> (ø)
superset-frontend/src/components/Button.jsx	88.88% <ø> (ø)
...et-frontend/src/components/RefreshChartOverlay.tsx	90.00% <80.00%> (ø)
superset-frontend/src/chart/Chart.jsx	66.66% <100.00%> (ø)
superset-frontend/src/components/Loading.tsx	100.00% <100.00%> (ø)
superset-frontend/src/reduxUtils.ts	70.88% <0.00%> (-8.87%)	⬇️
superset-frontend/src/SqlLab/actions/sqlLab.js	61.57% <0.00%> (-5.25%)	⬇️
superset-frontend/src/SqlLab/reducers/sqlLab.js	39.09% <0.00%> (-1.65%)	⬇️
...rontend/src/SqlLab/components/TabbedSqlEditors.jsx	80.95% <0.00%> (-0.87%)	⬇️
superset/security/manager.py	88.77% <0.00%> (-0.27%)	⬇️
... and 43 more

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[rusackas]

@etr2460 This PR is like pulling a loose thread on a sweater... I simplified a few more things, by consolidating some global LESS into the component, and removing the className in favor of additional "position" options. I hope this all makes sense. It seems simpler to me, anyway. I think the only recognizable visual diff is that the "inline" style is 10px narrower, which looks better to my eye, in the one place it's used:

[etr2460]

lgtm with the exception of the one cleanup line

[nytai]

Looks like this instance needs to be updated too: https://github.com/preset-io/incubator-superset/blob/master/superset-frontend/src/components/ListView/ListView.tsx#L120