AndroidConfig missing direct_boot_ok field

[BradEwing]

The firebase documentation explicitly lists a direct_boot_ok field for the AndroidConfig payload, but this is missing in the Go SDK.

[google-oss-bot]

I found a few problems with this issue:

• I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.
• This issue does not seem to follow the issue template. Make sure you provide all the required information.