[NOTICKET][DB] fix mysql pipeline

[KM-437][DB] add mysql, sqlserver, bigquery, snowflake connections

[NOTICKET][DB] menyesuaikan format struktur db_pipeline sesuai dengan file lain

[DB] fix/rename db_pipeline.py

[NOTICKET] new metadata format for cleaner code

[KM-441] add mean and median

[NOTICKET][DB] refactor code to new repo