Allow passing of configs when creating new databases

We should be able to pass database specific configs (e.g., leveldb config file) when creating a new database in Larry.

Start by locating Larry's database-creation entry point and reviewing how its different key-value database backends are initialized. Determine how database-specific configuration, such as a LevelDB config file, should be represented and passed. Done means callers can provide those configs when creating a new database without breaking existing backends.

Written by the indexing model from the issue text.