Support for other device clouds like BrowserStack

**Is your feature request related to a problem? Please describe.**
Currently, there is no way to integrate with a device cloud like BrowserStack and SauceLabs.

**Describe the solution you'd like**
Being able to start a session on one of the device clouds. They use Appium AFAIK and I don't think Airtest can start a session through Appium and connect to the remote device.

**Describe alternatives you've considered**
Not sure yet.