Various fixes to roborockvacuum

[rytilahti]

• Include descriptors from status() response. This performs I/O during the initialization to find out which information is available. Alternative would be changing updatehelper.py to collect the descriptors from all embedded updates, unsure what's the best approach.
• Fix exposing vacuum state.
• Expose fan speed presets.

Related to https://github.com/rytilahti/homeassistant-xiaomi-ng/issues/1

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 71.42857% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 81.42%. Comparing base (4083283) to head (8edabc1).

Files	Patch %	Lines
miio/integrations/roborock/vacuum/vacuum.py	16.66%	5 Missing :warning:
miio/device.py	0.00%	1 Missing and 1 partial :warning:
miio/descriptorcollection.py	93.33%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1916 +/- ## ========================================== - Coverage 81.43% 81.42% -0.02% ========================================== Files 193 193 Lines 18604 18628 +24 Branches 4032 4041 +9 ========================================== + Hits 15150 15167 +17 - Misses 3173 3179 +6 - Partials 281 282 +1 ```

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