[Desktop] SMS plugin no longer creates desktop notifications -- Old functionality still supported by notifications plugin

Summary:
Drop support for creating notifications from the SMS plugin. The old usecase is better handled by the notifications plugin reply box anyway

Rename packets defined in SMS plugin from PACKET_TYPE_TELEPHONY_* to PACKET_TYPE_SMS_*

Update TELEPHONY plugin packet description to point to SMS plugin

Define TELEPHONY_REQUEST_MUTE packet to replace old TELEPHONY_REQUEST with mute event field

Please see Android-side patch here: D15544

Test Plan:
I see four test cases, based on the version of the app being used, where "old" means any version built with sources not containing this revision and "new" means any version built with sources using this revision:
 - New Android vs. New Desktop
   - Supported and works for me
 - New Android vs. Old Desktop
   - Supported and works for me
 - Old Android vs. New Desktop
   - Not supported - Download a new app from the Play store or F-Droid
 - Old Android vs. Old Desktop
   - If this is broken, it is not my fault :)

In the supported use cases:
 - Test SMS reply
   - Receive SMS (or MMS!) message
   - Verify that the //notification// plugin forwards a replyable notification and that replying works
 - Test incoming call ringer mute
   - Enable ringer volume (not vibrate)
   - Receive phone call
   - Verify a desktop notification with a Mute button appears
   - Verify that clicking the mute button causes the phone to stop making the ringer noise (vibration not affected)

Reviewers: #kde_connect, albertvaka, nicolasfella

Reviewed By: #kde_connect, albertvaka, nicolasfella

Subscribers: nicolasfella, kdeconnect

Tags: #kde_connect

Differential Revision: https://phabricator.kde.org/D15543