Summary:
Update sms app model to use new conversationUpdated signal

Filter incoming messages which belong to a different conversation than the one currently being viewed

See Android-side diff D15360 which adds support for sending live updates when a new message is sent or received

Test Plan:
This patch relies on D15360 for Android-side support
  - Positive case:
    - Open a conversation in the SMS app
    - Receive a new message into that conversation (text yourself?)
    - Verify that the new message appears at the bottom of the appropriate conversation
  - Negative case:
    - Open a conversation in the SMS app
    - Receive a new message into a different conversation (text yourself?)
    - Verify that the new message does *not* appear in the open conversation

Reviewers: #kde_connect, nicolasfella

Reviewed By: #kde_connect, nicolasfella

Subscribers: nicolasfella, kdeconnect

Tags: #kde_connect

Differential Revision: https://phabricator.kde.org/D15409