[SMS App] Fix sending simple SMS
Summary
In kdeconnect-kde!316 (merged) we made some changes which are not backwards-compatible with the Android app. Since we have not yet released the Android app since those changes, we have hopefully not broken anybody but me.
However, this might be related to a recent bug: https://bugs.kde.org/show_bug.cgi?id=425638
Also updates some of the header comments for the recent changes
Test Plan
Before:
Sending SMS would silently fail
After:
Sending SMS throws an IllegalArgumentException
With kdeconnect-kde!320 (merged), SMS can be sent normally
Edited by Simon Redman