Update examples to use key and TLS

Signed-off-by: Mathias L. Baumann <mathias.baumann@frequenz.com>

Author: Marenz

src/frequenz/dispatch/_dispatcher.py

@@ -62,11 +62,19 @@ class Dispatcher:
         async def run():
             host = os.getenv("DISPATCH_API_HOST", "localhost")
             port = os.getenv("DISPATCH_API_PORT", "50051")
+            key  = os.getenv("DISPATCH_API_KEY", "some-key")
 
             service_address = f"{host}:{port}"
-            grpc_channel = grpc.aio.insecure_channel(service_address)
-            microgrid_id = 1
-            dispatcher = Dispatcher(microgrid_id, grpc_channel, service_address)
+            grpc_channel = grpc.aio.secure_channel(
+                service_address,
+                credentials=grpc.ssl_channel_credentials()
+            )
+            dispatcher = Dispatcher(
+                microgrid_id=1,
+                grpc_channel=grpc_channel,
+                svc_addr=service_address,
+                key=key
+            )
             await dispatcher.start()
 
             actor = MagicMock() # replace with your actor
@@ -110,12 +118,20 @@ async def run():
         async def run():
             host = os.getenv("DISPATCH_API_HOST", "localhost")
             port = os.getenv("DISPATCH_API_PORT", "50051")
+            key  = os.getenv("DISPATCH_API_KEY", "some-key")
 
             service_address = f"{host}:{port}"
-            grpc_channel = grpc.aio.insecure_channel(service_address)
-            microgrid_id = 1
-            dispatcher = Dispatcher(microgrid_id, grpc_channel, service_address)
-            dispatcher.start()  # this will start the actor
+            grpc_channel = grpc.aio.secure_channel(
+                service_address,
+                credentials=grpc.ssl_channel_credentials()
+            )
+            dispatcher = Dispatcher(
+                microgrid_id=1,
+                grpc_channel=grpc_channel,
+                svc_addr=service_address,
+                key=key
+            )
+            await dispatcher.start()  # this will start the actor
 
             events_receiver = dispatcher.lifecycle_events.new_receiver()
 
@@ -146,11 +162,21 @@ async def run():
         async def run():
             host = os.getenv("DISPATCH_API_HOST", "localhost")
             port = os.getenv("DISPATCH_API_PORT", "50051")
+            key  = os.getenv("DISPATCH_API_KEY", "some-key")
 
-            service_address = f"{host}:{port}"
-            grpc_channel = grpc.aio.insecure_channel(service_address)
             microgrid_id = 1
-            dispatcher = Dispatcher(microgrid_id, grpc_channel, service_address)
+
+            service_address = f"{host}:{port}"
+            grpc_channel = grpc.aio.secure_channel(
+                service_address,
+                credentials=grpc.ssl_channel_credentials()
+            )
+            dispatcher = Dispatcher(
+                microgrid_id=microgrid_id,
+                grpc_channel=grpc_channel,
+                svc_addr=service_address,
+                key=key
+            )
             await dispatcher.start()  # this will start the actor
 
             # Create a new dispatch