Add wrapper for libsql

[rober-tm]

Currently, migrating data from libsql-based services like Turso DB or PocketBase to Supabase can be a multi-step process involving data dumps and imports. This adds friction for users looking to transition to Supabase.

Describe the solution you'd like
Implement a Foreign Data Wrapper (FDW) for libsql. This would allow Supabase users to directly query and interact with libsql databases (e.g., Turso, PocketBase instances) from within their PostgreSQL instance.

Describe alternatives you've considered
Manual data export/import (e.g., CSV, SQL dumps) is the current alternative, but it's less efficient for ongoing migrations or for accessing data in a hybrid setup.

Additional context
Adding a libsql FDW would significantly simplify the migration path for users of libsql-compatible databases, making Supabase a more attractive option and lowering the barrier to adoption for this user segment. It could also enable more complex data integration scenarios.

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