Add metadata operations (includes Arrow conversion)

Added operations for metadata retrieval GetSchemas, GetTables and GetColumns + translations.
Also added a utility class to be able to convert data in a ColumnBasedSet to Arrow, as the metadata operations in ThiftServer do not return results in Arrow format.

Added unit tests + manual tests with modified client

Author: Sander Goos <sander.goos@databricks.com>

Author: sander-goos