MQTT: Birdseye enabled/disabled and mode change support (#8291)

* support enabled and mode change for birdseye via mqtt

* resolve feedback from PR review
https://github.com/blakeblackshear/frigate/pull/8291#discussion_r1370083613

* change birdseye mode topic to set

* type in the docs

* these commented out lines should have never been in here

frigate/config.py

@@ -501,6 +501,14 @@ class BirdseyeModeEnum(str, Enum):
     motion = "motion"
     continuous = "continuous"
 
+    @classmethod
+    def get_index(cls, type):
+        return list(cls).index(type)
+
+    @classmethod
+    def get(cls, index):
+        return list(cls)[index]
+
 
 class BirdseyeConfig(FrigateBaseModel):
     enabled: bool = Field(default=True, title="Enable birdseye view.")