[2/3] Telephony: Flip to Mute/Reject Call

Call Settings - add menu entry

PS2 - PS4: Code Cleanup

Base: https://gerrit.omnirom.org/#/c/4668/
InCallUI: https://gerrit.omnirom.org/#/c/4669/

Change-Id: Ic011c5b9e10439fc900b1302f7e07dde494b2e5b