refactor: adopt --app as celery global option

[shawnzhu]

SUMMARY

This is the step 1 of upgrading to Celery 5

Celery 5.0 introduces a new CLI implementation which isn’t completely backwards compatible.
The global options can no longer be positioned after the sub-command. Instead, they must be positioned as an option for the celery command like so:

celery --app path.to.app worker

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue: Worker failed to start b/c of WRONGPASS invalid username-password pair. #14925
• 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 #15053 (decb90a) into master (3f527c7) will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #15053      +/-   ##
==========================================
+ Coverage   77.76%   77.78%   +0.02%     
==========================================
  Files         966      966              
  Lines       49628    49628              
  Branches     6314     6314              
==========================================
+ Hits        38591    38604      +13     
+ Misses      10836    10823      -13     
  Partials      201      201              

Flag	Coverage Δ
hive	81.43% <ø> (ø)
mysql	81.70% <ø> (ø)
postgres	81.72% <ø> (?)
presto	81.43% <ø> (+<0.01%)	⬆️
python	82.25% <ø> (+0.04%)	⬆️
sqlite	81.35% <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/presto.py	90.31% <0.00%> (+0.42%)	⬆️
superset/views/base_api.py	98.28% <0.00%> (+0.42%)	⬆️
superset/db_engine_specs/postgres.py	96.96% <0.00%> (+1.01%)	⬆️
superset/sql_validators/postgres.py	100.00% <0.00%> (+50.00%)	⬆️

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[shawnzhu]

I hope this PR will make review of #14926 (a downstream dependency) easier

[nytai]

@shawnzhu thanks for the contribution! Looks like this change is compatible with the current version of celery so happy to merge once CI passes. As for #14926, it will require more thorough testing of our celery dependant features as it is a significant change.

[shawnzhu]

@nytai Thanks for the feedback! Now i can get #14926 to pass CI after this is merged