RESTRICT AUTOMERGE Merge multiple requests by an app in the same task upwards (u)

Merge older dialogs into newer ones, if an app makes multiple requests.

(NOTE: this is a cherry-pick of of a change originally authored by
ntmyren, with merge conflicts resolved.)

Bug: 313909156
Test: atest PermissionTest23#testAppCanOnlyShowOneDialog
(cherry picked from commit 6edd098221133ffa0cd1e930b5c9aa593224313e)
(cherry picked from commit 614473242f9e05a3f6e5e09ae8f18851c5061a15)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:87809935eb97150b31a7497c9fcb641272f9c252)
Merged-In: I25f72c30c22429472bfc75073431f84431debd7b
Change-Id: I25f72c30c22429472bfc75073431f84431debd7b