Improve handling of sqlite:// in-memory performance trick

Some of the implementations have been using the ability to connect to an in-memory sqlite database to improve on performance. This is particularly notable for Windows systems.
However, the in-memory database does not yet function with Felis. Some code changes are needed to take the Felis path and pass it along so that the in-memory database will also have that schema.

Likely the easiest change is to add `felis_schema` as an optional parameter in `astrodb.Database` to specify the path to the Felis schema and then pass that along to `create_database` when the in-memory database is being created.