Mms: Add close button for removing subject as a new UX path instead of relying on the depracated onKeyListener

- Vector FTW

Change-Id: I69b1b95cd01f38d3801e33eff6a3dd9c4941fab6
Fix hint text color in quick popup with light theme

Change-Id: I18b886cc7a0a31e3e0e3d2e26e22193feaa56500