Import homekit in the executor to avoid blocking the event loop (#111809)

`homekit import took 0.635 seconds (loaded_executor=False)`

not sure how I missed this one

homeassistant/components/homekit/manifest.json

@@ -6,6 +6,7 @@
   "config_flow": true,
   "dependencies": ["ffmpeg", "http", "network"],
   "documentation": "https://www.home-assistant.io/integrations/homekit",
+  "import_executor": true,
   "iot_class": "local_push",
   "loggers": ["pyhap"],
   "requirements": [