Use org.chromium.url.Origin in AWMI cache key

The initial Android WebView Media Integrity token provider cache
implementation used a lossy representation of the page origin that was a
URI-ified string-ified origin-ized GURL of the last committed URL. This
lost the token for opaque origins and reduced non-standard URLs to empty
strings, which were previously uncached to avoid conflicts.

This change modifies the cache to use Origin directly from last
committed origin. This makes the cache work for all origins (respecting
opaqueness) and avoids confusion caused by previously empty-stringified
origins.

testErrorsMappedRequestToken's mock calling expectations has been
updated to accommodate the new caching behavior.

testTokenProviderNotReusedIfInvalid has been disabled. This test was
previously passing erroneously, due to previous test and caching
behavior hiding the reality that cache invalidation has not actually
been implemented. It is to be resolved in a separate change for
crbug.com/333912408.

Bug: 333912408
Change-Id: Ieea11379eac7cf9c702ab93c96acc0e16c5f5f3e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5453553
Reviewed-by: Peter Beverloo <peter@chromium.org>
Commit-Queue: Ashley Newson <ashleynewson@chromium.org>
Reviewed-by: Peter Pakkenberg <pbirk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1287423}