Signal: Fix signal handlers for uvicorn

Add the ability to override uvicorn's signal handler in addition
to using main's signal handler for any SIGINTs before the API server
starts.

Signed-off-by: kingbri <bdashore3@proton.me>

common/signals.py

@@ -0,0 +1,23 @@
+import signal
+import sys
+from loguru import logger
+from types import FrameType
+
+
+def signal_handler(*_):
+    """Signal handler for main function. Run before uvicorn starts."""
+
+    logger.warning("Shutdown signal called. Exiting gracefully.")
+    sys.exit(0)
+
+
+def uvicorn_signal_handler(signal_event: signal.Signals):
+    """Overrides uvicorn's signal handler."""
+
+    default_signal_handler = signal.getsignal(signal_event)
+
+    def wrapped_handler(signum: int, frame: FrameType = None):
+        logger.warning("Shutdown signal called. Exiting gracefully.")
+        default_signal_handler(signum, frame)
+
+    signal.signal(signal_event, wrapped_handler)