chore: Add Druid SQL time grains for parity with Druid NoSQL

[john-bodley]

SUMMARY

Adding Druid SQL time grains for parity with Druid NoSQL per here. Note the Druid NoSQL connector supports simple natural language whereas the SQL connector does not.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

AFTER

TESTING INSTRUCTIONS

Verified the SQL logic adhered to other database engine specifications.

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 #15320 (454f831) into master (b295c6a) will decrease coverage by 0.15%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #15320      +/-   ##
==========================================
- Coverage   77.16%   77.01%   -0.16%     
==========================================
  Files         973      973              
  Lines       50523    50523              
  Branches     6184     6184              
==========================================
- Hits        38986    38909      -77     
- Misses      11331    11408      +77     
  Partials      206      206              

Flag	Coverage Δ
hive	?
mysql	81.70% <ø> (ø)
postgres	81.72% <ø> (ø)
python	81.81% <ø> (-0.30%)	⬇️
sqlite	81.36% <ø> (ø)

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

Impacted Files	Coverage Δ
superset/db_engine_specs/base.py	87.97% <ø> (-0.41%)	⬇️
superset/db_engine_specs/druid.py	88.63% <ø> (ø)
superset/db_engines/hive.py	0.00% <0.00%> (-82.15%)	⬇️
superset/db_engine_specs/hive.py	69.20% <0.00%> (-17.21%)	⬇️
superset/views/database/mixins.py	81.03% <0.00%> (-1.73%)	⬇️
superset/db_engine_specs/presto.py	83.36% <0.00%> (-1.06%)	⬇️
superset/connectors/sqla/models.py	88.22% <0.00%> (-0.24%)	⬇️
superset/utils/core.py	88.93% <0.00%> (-0.13%)	⬇️

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[john-bodley]

@villebro would you mind re-reviewing this PR? I added all the additional time grains (not just week starting/ending) which have not previously been defined or the SQL connector. Let me know if this should be added in db_engine_specs/base.py (as defined) or whether db_engine_specs/druid.py should override the get_time_grains() method.

Furthermore I'm not sure if additional work is required, i.e., for Pandas post processing per here. Additionally I'm not sure if the custom time grain configuration logic actually works if these need to be defined within the post processing as mentioned above, i.e., can Superset really support custom time grains?

[villebro]

@villebro would you mind re-reviewing this PR? I added all the additional time grains (not just week starting/ending) which have not previously been defined or the SQL connector. Let me know if this should be added in db_engine_specs/base.py (as defined) or whether db_engine_specs/druid.py should override the get_time_grains() method.

I think this is fine. We have plans to introduce freeform timegrains (where easily supported), via regex or other pattern matching schemes. This would make it possible to do arbitrary time grains, like PT7M. Most engines support this fairly easily, but for others that are more restricted we would only support the built-in ones that have to be explicitly written out.

Furthermore I'm not sure if additional work is required, i.e., for Pandas post processing per here. Additionally I'm not sure if the custom time grain configuration logic actually works if these need to be defined within the post processing as mentioned above, i.e., can Superset really support custom time grains?

I think it's ok, at least for now, to just support the built-in time grains in the forecasting feature. But here we could probably fairly easily also support more custom increments via regex. I'd be happy to add this as soon as someone requests it or when we start working on the arbitrary precision time grain feature.

[villebro]

LGTM