Merged PR 348: #2462 - Refactor of DatabaseClient and DatabaseServer

## Summary
Refactor of `DatabaseClient` and `DatabaseService` to update how connection IDs are generated. These are now provided by DatabaseService when establishing a connection.
Creation of `DatabaseClientConnection` class. This is used by `DatabaseClient` to hold a dictionary of active db connections.

## Test process
Tests have been updated to reflect the changes and all pass

## Checklist
- [X] PR is linked to a **work item**
- [X] **acceptance criteria** of linked ticket are met
- [X] performed **self-review** of the code
- [X] written **tests** for any new functionality added with this PR
- [X] updated the **documentation** if this PR changes or adds functionality
- [ ] written/updated **design docs** if this PR implements new functionality
- [X] updated the **change log**
- [X] ran **pre-commit** checks for code style
- [X] attended to any **TO-DOs** left in the code

Related work items: #2462

src/primaite/simulator/system/services/ftp/ftp_server.py

@@ -61,7 +61,7 @@ class FTPServer(FTPServiceABC):
             return payload
 
         if payload.ftp_command == FTPCommand.QUIT:
-            self.remove_connection(connection_id=session_id)
+            self.terminate_connection(connection_id=session_id)
             payload.status_code = FTPStatusCode.OK
             return payload