Add signal_handler helper method

(cherry picked from commit 8c7b1b0)

Author: NickCao

packages/jumpstarter-cli-common/jumpstarter_cli_common/signal.py

@@ -0,0 +1,22 @@
+import signal
+
+import asyncclick as click
+from anyio import open_signal_receiver
+from anyio.abc import CancelScope
+
+
+# Reference: https://github.com/agronholm/anyio/blob/4.9.0/docs/signals.rst
+async def signal_handler(scope: CancelScope):
+    with open_signal_receiver(signal.SIGINT, signal.SIGTERM) as signals:
+        async for signum in signals:
+            match signum:
+                case signal.SIGINT:
+                    click.echo("SIGINT pressed, terminating", err=True)
+                case signal.SIGTERM:
+                    click.echo("SIGTERM received, terminating", err=True)
+                case _:
+                    pass
+
+            scope.cancel()
+
+            break