[pausemusic] Add option to not unpause music once call has finished.

Summary

This patch adds an extra option in the configuration for the Pause media during calls panel, "Unpause when call has finished."

When this box is checked (as it is by default), the plugin acts as it does before the patch, which is to immediately resume the media when KDE Connect is told the call ended.

When the box is unchecked, the media will remain paused until it is manually resumed by the user.

This was requested by Issue #12, and I was actually going to write a similar issue until I saw that one.

Often times, I will receive a call while I have headphones on with media playing. Once the call is ended, my headphones are still off (or I'm in another room), and the media will resume without my presence. This solves this issue without disrupting the current functionality.

Implements #12 Bug: 421815

Test Plan

I tested this by calling my number several times with a separate phone (not linked to KDE Connect) with the option enabled and disabled to make sure the desired effect was occurring.

Note: I have not tested this on Windows, but due to the simplicity of the patch, it will most likely work as advertised.