Add Superset as a plugin

• https://superset.apache.org/
• https://github.com/apache/superset
• https://pypi.org/project/apache-superset

meltano add analyzer superset

meltano invoke superset db upgrade # Run automatically?
meltano invoke superset fab create-admin
meltano invoke superset init # Run automatically?
meltano invoke superset run

Meltano can manage Superset configuration (https://superset.apache.org/docs/installation/configuring-superset) by allowing values to be set for the keys in https://github.com/apache/superset/blob/master/superset/config.py, automatically generating superset_config.py, and pointing Superset there by using the SUPERSET_CONFIG_PATH env var. Users should also be able to set SUPERSET_CONFIG_PATH (or meltano config superset set config_path <path>) themselves to use their own config file.

Ideally, Meltano would also be able to inject database connection strings corresponding to loaders directly into Superset so that these don't need to be managed in two places: https://superset.apache.org/docs/databases/installing-database-drivers, https://superset.apache.org/docs/databases/postgres. Possibly through the DB_CONNECTION_MUTATOR setting? https://github.com/apache/superset/issues/9045