chore: improve performance on bootstrap permissions

[dpgaspar]

SUMMARY

Improves performance when fetching user permissions for bootstrap data. Previously we were doing 1 query per user role, now it will just do 1 query no matter how many roles a user has.

Measured get_permissions execution time, on 100 executions the avg time was:

0.019353721141815185 <- previous call
0.00747002124786377 <- new call

~60% speed improvement

Performance improvement on FAB: https://github.com/dpgaspar/Flask-AppBuilder/blob/master/flask_appbuilder/security/sqla/manager.py#L398

Followup PR from this: #21313

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

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

[codecov]

Codecov Report

Merging #22083 (bf00314) into master (cd1b379) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master   #22083   +/-   ##
=======================================
  Coverage   67.07%   67.07%           
=======================================
  Files        1815     1815           
  Lines       69575    69572    -3     
  Branches     7486     7486           
=======================================
+ Hits        46665    46667    +2     
+ Misses      20974    20969    -5     
  Partials     1936     1936           

Flag	Coverage Δ
hive	52.84% <0.00%> (+0.01%)	⬆️
mysql	78.40% <100.00%> (+<0.01%)	⬆️
postgres	78.46% <100.00%> (+<0.01%)	⬆️
presto	52.74% <0.00%> (+0.01%)	⬆️
python	81.58% <100.00%> (+0.01%)	⬆️
sqlite	76.92% <100.00%> (+<0.01%)	⬆️
unit	51.22% <0.00%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
superset/views/utils.py	80.69% <100.00%> (-0.15%)	⬇️
superset/db_engine_specs/base.py	89.21% <0.00%> (+0.05%)	⬆️
superset/db_engine_specs/presto.py	88.22% <0.00%> (+0.44%)	⬆️
superset/db_engine_specs/bigquery.py	82.58% <0.00%> (+0.53%)	⬆️
superset/db_engine_specs/druid.py	83.33% <0.00%> (+2.38%)	⬆️

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[villebro]

LGTM. These types of improvements can have a huge cumulative effect. It would be great to try to see if there's other similar low hanging fruit in the codebase.