* chore move sql_execution_context to sqllab package
* add new helper methods into base Dao
* refactor separate get existing query concern from command
* refactor separate query access validation concern
* refactor separate get query's database concern from command
* refactor separate get query rendering concern from command
* refactor sqllab_execution_context
* refactor separate creating payload for view
* chore decouple command from superset app
* fix pylint issues
* fix failed tests
* fix pylint issues
* fix failed test
* fix failed black
* fix failed black
* fix failed test