Update fitbit error handling (#101304)

* Update fitbit error handling

* Update exceptions to inherit HomeAssistantError and add reason code

* Revert config flow exception mapping hack

homeassistant/components/fitbit/exceptions.py

@@ -0,0 +1,14 @@
+"""Exceptions for fitbit API calls.
+
+These exceptions exist to provide common exceptions for the async and sync client libraries.
+"""
+
+from homeassistant.exceptions import HomeAssistantError
+
+
+class FitbitApiException(HomeAssistantError):
+    """Error talking to the fitbit API."""
+
+
+class FitbitAuthException(FitbitApiException):
+    """Authentication related error talking to the fitbit API."""