Change AppPicker theme from dialog to full screen

AppPicker used in devceloper options, it will show apps list with
package name in a dialog.
But sometimes it will mis-alignment with package name.
So we change theme from dialog to full screen and set widget_frame
visibility to GONE.

Bug: 151150544
Test: manual
Change-Id: I8f04ab7967288801e5e13ecccf037d6ed09ec71c