Summary:
Android devices don't always know their own serial.
But we do a certificate exchange using adb from the desktop, so we can provide it in the response.
After this the client will provide it every time it connects, so we can do things like filter plugins by device id.
For apps that have already done cert exchange, they'll continue to use 'unknown' as their id until they do it again with an up to date version of sonar.
We can think about forcefully stopping that, but I haven't done it.
Reviewed By: danielbuechele
Differential Revision: D9481460
fbshipit-source-id: f8932699711ebbec4260fabe32f87e6cdff920f2
edff177c3f