What this PR does / why we need it:

• Implemented DatabricksUCOfflineStoreConfig (inheriting from SparkOfflineStoreConfig) to specify workspace, token, cluster_id, default_catalog, and default_schema.
• Implemented get_databricks_session helper that securely handles active sessions or connects remotely using Databricks Connect V2 configurations.
• Implemented DatabricksUCOfflineStore which inherits from SparkOfflineStore, overriding operations to guarantee Databricks session initialization before executing queries.
• Registered "databricks_uc" in the first-class OFFLINE_STORE_CLASS_FOR_TYPE mapping.

Which issue(s) this PR fixes:

Partially Fixes - #6499

Checks

• I've made sure the tests are passing.
• My commits are signed off (git commit -s)
• My PR title follows conventional commits format

Testing Strategy

• Unit tests
• Integration tests
• Manual tests
• Testing is not required for this change