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/web_server/web_server.py

@@ -11,7 +11,7 @@ from primaite.simulator.network.protocols.http import (
 )
 from primaite.simulator.network.transmission.network_layer import IPProtocol
 from primaite.simulator.network.transmission.transport_layer import Port
-from primaite.simulator.system.applications.database_client import DatabaseClient
+from primaite.simulator.system.applications.database_client import DatabaseClientConnection
 from primaite.simulator.system.services.service import Service
 from primaite.simulator.system.software import SoftwareHealthState
 
@@ -48,6 +48,7 @@ class WebServer(Service):
         super().__init__(**kwargs)
         self._install_web_files()
         self.start()
+        self.db_connection: Optional[DatabaseClientConnection] = None
 
     def _install_web_files(self):
         """
@@ -108,9 +109,11 @@ class WebServer(Service):
 
             if path.startswith("users"):
                 # get data from DatabaseServer
-                db_client: DatabaseClient = self.software_manager.software.get("DatabaseClient")
                 # get all users
-                if db_client.query("SELECT"):
+                if not self.db_connection:
+                    self._establish_db_connection()
+
+                if self.db_connection.query("SELECT"):
                     # query succeeded
                     self.set_health_state(SoftwareHealthState.GOOD)
                     response.status_code = HttpStatusCode.OK
@@ -123,6 +126,11 @@ class WebServer(Service):
             response.status_code = HttpStatusCode.INTERNAL_SERVER_ERROR
             return response
 
+    def _establish_db_connection(self) -> None:
+        """Establish a connection to db."""
+        db_client = self.software_manager.software.get("DatabaseClient")
+        self.db_connection: DatabaseClientConnection = db_client.get_new_connection()
+
     def send(
         self,
         payload: HttpResponsePacket,