throw PlatformNotReady if unable to connect

[aav7fl]

Throw PlatformNotReady for when the device disconnects, or when the Home Assistant is booting and the ADB server is not ready yet.

Description:

When HA is ready before my ADB server in my docker container, or if my device disconnects from the network temporarily, HA loses connection and requires a restart. Instead, I think it should throw a PlatformNotReady so it will retry it, and do it in a back-off manner.

I tested this on my own network and it fixed my problem. I think others should benefit from this too.

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

If the code communicates with devices, web services, or third-party tools:

• New dependencies are only imported inside functions that use them (example).

[andrewsayre]

Thank you! Can merge when build passes.