Add xiamoi_miio the water_box / mop status

[JJdeVries]

Proposed change

I would like to track the mop status to enable reminders to use the mop after a certain time has passed.

Here is a link to the relevant function of the miio dependency:
https://github.com/rytilahti/python-miio/blob/master/miio/vacuumcontainers.py#L173

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[probot-home-assistant]

Hey there @rytilahti, @syssi, @starkillerOG, mind taking a look at this pull request as its been labeled with an integration (xiaomi_miio) you are listed as a codeowner for? Thanks!
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[rytilahti]

Looks straightforward to me, how about the naming of the variable? Should it be about the water box or the mop?

[JJdeVries]

Looks straightforward to me, how about the naming of the variable? Should it be about the water box or the mop?

I was kinda confused by the naming as wel. For the S5 Max that I have here this property only becomes true if I connect the mop to the robot, whereas the waterbox is always connected. So for me this naming is more intuitive, but I'm unsure how other models handle this.

[rytilahti]

Hmm, I see, that's a tricky one but I'm open to have it as mop_attached. I hope someone having a non-S5max with a mop could confirm if the sensor is merely used for the mop, because if so, we should probably rename the property in python-miio at some point.

For the naming of the state attribute, I just checked if any other vacuum mentions mopping, and looks like only roomba/braava.py has anything relevant, and it exposes both detected_pad and tank_present. @shenxn, do you think it'd be worth to standardize the naming of mop availability?

[MartinHjelmare]

Let's merge this for now.