debos: rootfs: Install adbd

[lool]

After installation, adbd just comes up automatically on boot and can be
used to open shells or push/pull files.

Fixes: #24

[lool]

Tested by installing adbd on an RB1 provisioned with a recent flat image from CI and rebooting; I can:

• open a shell with adb shell
• pull files with adb pull /etc/passwd

Note that this only works on RB1 if you set DIP switch 6 on "DIP_SW_1" to ON, which routes SoM's USB 3.0 to the type-C port instead of the built-in USB hub.

[ricardosalveti]

Note that this only works on RB1 if you set DIP switch 6 on "DIP_SW_1" to ON, which routes SoM's USB 3.0 to the type-C port instead of the built-in USB hub.

Do we need to have this documented somewhere?

[lool]

Note that this only works on RB1 if you set DIP switch 6 on "DIP_SW_1" to ON, which routes SoM's USB 3.0 to the type-C port instead of the built-in USB hub.

Do we need to have this documented somewhere?

Yes, perhaps in something like a wiki :D