Add common parent class for DuckDB and Clickhouse classes

[Msa360]

Description of changes

• Improvements
  • New CommonDB class that the DuckDB and Clickhouse class can both inherit from. DuckDB used to inherit from Clickhouse.
  • Applied the inheritance to both DuckDB and Clickhouse classes.
  • Put the schemas in the commondb.py file since both classes need them.
  • Less confusing names for the db_array_schema_to_clickhouse_schema and clickhouse_to_duckdb_schema functions.

Test plan

Passed pytest

Documentation Changes

No changes for the user-side api.