fix: Always use temporal type for dttm columns [ID-2]

[kgabryje]

SUMMARY

If a column is marked as is_dttm, always return it's generic type as TEMPORAL. This change fixes a bug in databases like Druid that sometimes return dates as string instead of datetime format.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

1. Set a column as temporal in Edit Dataset modal
2. Add that column to chart
3. Verify that coltype returned for that column in response is equal to 2 - Temporal

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• 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

CC @jinghua-qa @junlincc

[codecov]

Codecov Report

Merging #17458 (9ee7201) into master (e2a429b) will decrease coverage by 0.21%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##           master   #17458      +/-   ##
==========================================
- Coverage   76.94%   76.73%   -0.22%     
==========================================
  Files        1042     1042              
  Lines       56248    56257       +9     
  Branches     7784     7784              
==========================================
- Hits        43282    43168     -114     
- Misses      12707    12830     +123     
  Partials      259      259              

Flag	Coverage Δ
hive	?
mysql	81.95% <81.81%> (-0.01%)	⬇️
postgres	81.96% <81.81%> (-0.01%)	⬇️
presto	?
python	82.05% <81.81%> (-0.42%)	⬇️
sqlite	81.64% <81.81%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
superset/charts/post_processing.py	67.74% <50.00%> (+0.26%)	⬆️
superset/charts/data/api.py	88.65% <75.00%> (+0.08%)	⬆️
superset/common/query_actions.py	92.85% <100.00%> (ø)
superset/utils/core.py	89.64% <100.00%> (-0.10%)	⬇️
superset/db_engines/hive.py	0.00% <0.00%> (-85.19%)	⬇️
superset/db_engine_specs/hive.py	69.49% <0.00%> (-16.99%)	⬇️
superset/db_engine_specs/presto.py	83.47% <0.00%> (-6.91%)	⬇️
superset/views/database/mixins.py	81.03% <0.00%> (-1.73%)	⬇️
superset/connectors/sqla/models.py	86.79% <0.00%> (-1.59%)	⬇️
superset/utils/webdriver.py	79.78% <0.00%> (-1.12%)	⬇️
... and 5 more

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[zhaoyongjie]

LGTM. frontend follow-up suggestion. If a string can't be parsed, we will use NaT or original text.

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