* Bump pylint version to 2.5.3
* Add a global disable for the most common new pylint error
* Fix a bunch of files containing very few errors
* More pylint tweakage, low-hanging fruit
* More easy stuff...
* Fix more erroring files
* Fix the last couple of errors, clean pylint!
* Black
* Fix mypy issue in connectors/druid/models.py
* [dashboard] Refactor API using SIP-35
* [dashboard] Fix, import
* [dashboard] more tests
* [dashboards] a misc of improvements
* [charts] Fix, DAO and tests
* [dashboards] small exceptions refactor
* [dashboards] lint
* [dashboards] Improves comments on base classes
* [dashboards] lint
