[PIX] View communicates the UI events via the listener

In this change, the view class communicates the UI events via the
UI event listener.

go/pix-ui-events

Note: The bottom sheet controller is mocked in tests because of which
the UI event listener can't be tested for dismissal cases.

Bug: 375089558, b/375088986
Change-Id: I1a78a2499ae28d1d95319b7fd48ac59b90a16a28
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5977027
Reviewed-by: Siyu An <siyua@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Vishwas Uppoor <vishwasuppoor@google.com>
Reviewed-by: Rouslan Solomakhin <rouslan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1381816}