[Fix] Fix is_local_domain to support backend objects

[Fix] Fix is_local_domain to support backend objects

The is_local_domain function was directly accessing module_state.local_domains
as a table, which caused it to always return false when local_domains was
configured as a backend object (MapBackend, CDBBackend, etc).

Fixed by:
- Moving get_from_source helper function before is_local_domain
- Using get_from_source to handle both plain tables and backend objects
- Updating return logic to handle different truthy values from backends