Use backend-provided fan speed presets for Xiaomi vacuums

This needs input from Xiaomi vacuum owners to verify that it does not break anything.
I have personally tested this on rockrobo v1 (old mapping).

Related issues/PRs:
home-assistant#32821
home-assistant#31268
home-assistant#27268

This is a WIP as it requires a new upstream release.
The PR is rytilahti/python-miio#643

homeassistant/components/xiaomi_miio/vacuum.py

@@ -60,8 +60,6 @@
     extra=vol.ALLOW_EXTRA,
 )
 
-FAN_SPEEDS = {"Silent": 38, "Standard": 60, "Medium": 77, "Turbo": 90, "Gentle": 105}
-
 ATTR_CLEAN_START = "clean_start"
 ATTR_CLEAN_STOP = "clean_stop"
 ATTR_CLEANING_TIME = "cleaning_time"
@@ -246,6 +244,7 @@ def __init__(self, name, vacuum):
         self.clean_history = None
         self.dnd_state = None
         self.last_clean = None
+        self._fan_speeds = None
 
     @property
     def name(self):
@@ -281,14 +280,14 @@ def fan_speed(self):
         """Return the fan speed of the vacuum cleaner."""
         if self.vacuum_state is not None:
             speed = self.vacuum_state.fanspeed
-            if speed in FAN_SPEEDS.values():
-                return [key for key, value in FAN_SPEEDS.items() if value == speed][0]
+            if speed in self._fan_speeds.values():
+                return [key for key, value in self._fan_speeds.items() if value == speed][0]
             return speed
 
     @property
     def fan_speed_list(self):
         """Get the list of available fan speed steps of the vacuum cleaner."""
-        return list(sorted(FAN_SPEEDS.keys(), key=lambda s: FAN_SPEEDS[s]))
+        return list(self._fan_speeds)
 
     @property
     def device_state_attributes(self):
@@ -372,8 +371,8 @@ async def async_stop(self, **kwargs):
 
     async def async_set_fan_speed(self, fan_speed, **kwargs):
         """Set fan speed."""
-        if fan_speed.capitalize() in FAN_SPEEDS:
-            fan_speed = FAN_SPEEDS[fan_speed.capitalize()]
+        if fan_speed.capitalize() in self._fan_speeds:
+            fan_speed = self._fan_speeds[fan_speed.capitalize()]
         else:
             try:
                 fan_speed = int(fan_speed)
@@ -453,6 +452,8 @@ def update(self):
             state = self._vacuum.status()
             self.vacuum_state = state
 
+            self._fan_speeds = self._vacuum.fan_speed_presets()
+
             self.consumable_state = self._vacuum.consumable_status()
             self.clean_history = self._vacuum.clean_history()
             self.last_clean = self._vacuum.last_clean_details()