Add ignore_tables list

When instantiating a `Database` object, there may be a need to provide a list of tables that are to be ignored. This can be useful to handle cases where those tables are created/managed separately from astrodbkit2.

Start at the Database constructor and inspect how tables are discovered or managed. Search the repository for Database initialization and table handling; done means a supplied ignore_tables list prevents those tables from being handled by AstrodbKit. The payload names no files or tests, so repository search is needed.

Written by the indexing model from the issue text.