Fix TalkBack page announcments in RecentsView

Because a PagedView has page a11y actions (PAGE_LEFT/RIGHT),
a11y services now identify recents apps as a pager.
Tweak the a11y event info to accomodate this so the announcements
are correct.
Also fix the CollectionItemInfo to have the correct page index.

Bug: 141899192
Test: Tested with TalkBack on device
Change-Id: Ic578bee8de26a41f0ab0e5468f1fd060ed21a7e1