Request focus in uninstaller activity for Wear

A dialog in Wear needs to be focused to allow for rotational input, but a dialog loses focus when it's hidden. To mitigate this, we are re-requetsing focus any time the dialog is shown again.

Bug: 417602569
Test: see https://buganizer.corp.google.com/issues/375325428#comment15
Flag: EXEMPT minor, Wear only change
Change-Id: I5dde00e6487dfa45d586afff373ed3e34b9c0b61