* Add function to clear connection cache.
* Update FDW to v1.9.0 - Add ability to clear connection cache by inserting into settings table.
* Update plugin sdk to v5.6.1
* fix listen unit tests
- Execute RefreshConnections asyncronously
- Add connection_state table to indicate the loading state of connections
- Optimise RefreshConnections by cloning connection schemas
- Add locking to ensure only a single instance of RefreshConnections runs
- Start executing queries without waiting for connections to load, add smart error handling to wait for required connection
- Optimise autocomplete for high connection count
- Autocomplete and inspect data available before all conections are refreshed
- Update file watcher to respond to CHMOD, so thaat it pickes up deletion of file contents
Closes#3394Closes#3267