feat: add statsd metrics to FAB rest API post, put and delete

[dpgaspar]

SUMMARY

Change at the BaseSupersetModelRestApi that enables metrics for FAB's post, put and delete REST API endpoints

Also couldn't help myself in doing a small refactor on datasets test to change self.assert<Cond> to assert since we prefer these now

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 #11362 into master will decrease coverage by 4.19%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #11362      +/-   ##
==========================================
- Coverage   65.78%   61.58%   -4.20%     
==========================================
  Files         838      838              
  Lines       39841    39847       +6     
  Branches     3655     3655              
==========================================
- Hits        26208    24540    -1668     
- Misses      13532    15126    +1594     
- Partials      101      181      +80     

Flag	Coverage Δ
#cypress	?
#javascript	62.63% <ø> (-0.01%)	⬇️
#python	60.95% <100.00%> (+0.03%)	⬆️

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

Impacted Files	Coverage Δ
superset/views/base_api.py	98.02% <100.00%> (+0.12%)	⬆️
superset-frontend/src/SqlLab/App.jsx	0.00% <0.00%> (-100.00%)	⬇️
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/explore/index.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/dashboard/index.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/setup/setupFormatters.js	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/explore/reducers/index.js	0.00% <0.00%> (-100.00%)	⬇️
... and 172 more

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[villebro]

LGTM