fix(cli): Log errors when adb command fails

[Plebshot]

As described in #3436, not having adb in the path (or having other problems with adb) fails silently.

The problem here is that the two adb commands for installing and starting the app are done on a new tokio background task without logging the result. Errors are propagated to the tasks handle, but the handle is detached and therefore never checked.

I wasn't sure what the best way to handle detached errors in the CLI is, so I went with simply logging errors instead of propagating them. Some open questions remain:

• Should we explicitly add adb as requirement in the docs for the mobile docs?
• Should we check for system dependencies beforehand for clearer error messages?

Fixes #3436