Add INTERACT_ACROSS_USERS permission for DocsUI AndroidManifest

Test: make aosp_x86_64-eng
Test: make flame-userdebug
Test: check INTERACT_ACROSS_USERS in /system/etc/permissions/com.android.documentsui.xml
Test: check INTERACT_ACROSS_USERS grant to DocumentsUI.apk
Test: atest DocumentsUITests:com.android.documentsui.PermissionsTest
Bug: 148198996

Change-Id: I99b7efee67d5d452fd64f29d436d65b8a04cf100