iwa: Prevent update of managed installed not allowlisted apps

Managed iwa allowlist is a new mechanism to prevent the installation and
updates of non-allowlisted apps. The feature is discussed in the linked
DD. This CL prevents update of  non-allowlisted managed apps (installed
by force-install policy).

The CL also introduces a method to bypass allowlist checks for unrelated
tests (it causes methods checking if app is allowlisted always return
true).

DD: go/iwa-allowlist-dd
Fixed: 410532802
Change-Id: Id8e7fe8d837a0e78f74fcce05e22a9e1333e2c2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6624438
Reviewed-by: Magdalena Skarbińska <mskarbinska@google.com>
Commit-Queue: Robert Ferens <rferens@google.com>
Reviewed-by: Andrew Rayskiy <greengrape@google.com>
Reviewed-by: Simon Hangl <simonha@google.com>
Cr-Commit-Position: refs/heads/main@{#1476540}