Update bookmarks.xml shortcuts to specify a role to invoke.

Update bookmarks.xml to allow specifying that ths shortcut should
launch the role holder for a given role.

Bug: 325050150
Test: atest WmTests:com.android.server.policy.ModifierShortcutTests
Flag: NA
Change-Id: Ifb06f229d0da4a31b69d3d75e9de2d07f53051cf