Check for text when adding CollectionInfo and CollectionItemInfo

Generally, the button's text is displayed next to the check box, but
Sound Settings uses its own views to display the text, distinct from
RadioGroup and RadioButton. This results in TalkBack announcing out
of list state too early, since the text content is not considered
part of the collection.

Add a check to exclude buttons with no text when counting the children
to be in the collection. Developers should be either setting the button
text or implementing their own views to appear alongside the buttons.

Bug: 149064784
Test: Added CTS test. Manual testing of Settings -> Sound -> Do no
disturb -> Advanced -> Set Duration for Quick Settings

Change-Id: Ie9abe4cccc4ab53e79a583b9a2ce45535dcf1cc0