refactor: test connection raises only command exceptions

[dpgaspar]

SUMMARY

Small refactor to test connection API and command to allow unsafe connections message surface back to the users and make the command only raise CommandException exceptions

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 #12307 (6487c80) into master (e660723) will decrease coverage by 15.67%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master   #12307       +/-   ##
===========================================
- Coverage   67.13%   51.46%   -15.68%     
===========================================
  Files        1002      466      -536     
  Lines       49289    16805    -32484     
  Branches     5006     4321      -685     
===========================================
- Hits        33091     8648    -24443     
+ Misses      16073     8157     -7916     
+ Partials      125        0      -125     

Flag	Coverage Δ
cypress	51.46% <ø> (+0.04%)	⬆️
javascript	?
python	?

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

Impacted Files	Coverage Δ
...uperset-frontend/src/dashboard/util/dnd-reorder.js	0.00% <0.00%> (-100.00%)	⬇️
...rset-frontend/src/dashboard/util/getEmptyLayout.js	0.00% <0.00%> (-100.00%)	⬇️
...dashboard/components/resizable/ResizableHandle.jsx	0.00% <0.00%> (-100.00%)	⬇️
.../src/dashboard/util/getFilterScopeFromNodesTree.js	0.00% <0.00%> (-93.48%)	⬇️
...set-frontend/src/views/CRUD/alert/ExecutionLog.tsx	11.76% <0.00%> (-88.24%)	⬇️
...src/dashboard/components/gridComponents/Header.jsx	10.52% <0.00%> (-86.85%)	⬇️
superset-frontend/src/components/IconTooltip.tsx	13.33% <0.00%> (-86.67%)	⬇️
...rc/dashboard/components/gridComponents/Divider.jsx	13.33% <0.00%> (-86.67%)	⬇️
...end/src/SqlLab/components/ExploreResultsButton.jsx	8.00% <0.00%> (-84.00%)	⬇️
...nd/src/views/CRUD/data/query/QueryPreviewModal.tsx	14.70% <0.00%> (-82.97%)	⬇️
... and 855 more

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[villebro]

Nice! 🎉