[feature req] List tables function for sql
Suggestion: introduce a function, something like `pandas.sql_list_tables(conn)` to look up available tables (shortcut for 
`pd.read_sql("SELECT * FROM sqlite_master WHERE type='table'", conn, index_col=["name"])` or 
`pd.read_sql("SELECT name FROM sqlite_master WHERE type='table'", conn)`). 

Like in [this `R` module](https://rstudio-pubs-static.s3.amazonaws.com/52614_1fa12c657ba7492092bd538205d7f02e.html)
