[TabModel] Refactor getNextTabIfClosed() to be shared

- Create TabModelImplUtil.java to share logic between TabModelImpl and
  TabCollectionTabModelImpl and make it easily unit-testable.
- Move getNextTabIfClosed() to this shared class and refactor it to
  be more readable.
- Change the implementation of getNextTabIfClosed() to work on a list
  of tabs rather than a single tab in the event multiple tabs are
  closing. This allows us to do a single selection per-close rather than
  doing a selection per-tab when remove/close is implemented in
  TabCollectionTabModelImpl.

Bug: 425656354
Change-Id: I42f8f75adaa1d8cfe4381cf93e580422094673e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6681276
Reviewed-by: Sky Malice <skym@chromium.org>
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1480109}