Fix radio buttons in IntentBuilderView

Intent builderview currently had a hierarchy consiting of:
RadioGroup -> LinearLayout -> RadioButton. However if the RadioButton is
not directly inside the RadioGroup, the RadioGroup has no effect on the
button.

Instead keep a list of all the RadioButtons we have and deselect all
others when a new button gets clicked.

Test: Manual
Change-Id: I65b9e1165ae3abc23b10f7eb8770a60f144aac82