[pickers] Disabled month is selected by default

[wscourge]

Steps to reproduce

It is important to understand, that at the time of writing it's July 2019.

1. Create picker with:

maxDate={moment().add(6, 'months')
views={['year', 'month']}
openTo="year"

2. Open the picker and select next year
3. Selected month is July, althought it is disabled

Expected behavior

No month should be selected - guess that's going to be hard, as it is not valid date due to moment deprecation warning.

An acceptable solution would be to set the selected month to anything that is not disabled.

Actual behavior

Selected month is one of the disabled months.

Live example

https://codesandbox.io/s/basicdatepicker-material-demo-forked-5czq6?file=/demo.tsx

Due to better active month visibility, I'm attaching the screenshot of my custom date picker as well:

Your Environment 🌎

Tech	Version
@material-ui/lab	v5.0.0-alpha.16

[oliviertassinari]

I think that we could at least display the months that are out of range disabled.

[flaviendelangle]

Fixed by #4814