Temp Fix ObjectModel Crash & Mic Mute Option

Summary:
Ref T5742, T5718

Reverted to ListModel as a temporary fix from ObjectModel which was causing random Segv Fault, Added option to mute mic

Test Plan: Stress testing the plasmoid to check for more crashes

Subscribers: plasma-devel

Tags: Plasma

Maniphest Tasks: T5742, T5718

Differential Revision: https://phabricator.kde.org/D5220