Notify the renderer when a navigation API traverse fails in the browser process

There are two main cases where navigation.traverseTo() will reach the
browser process, but the browser process will fail to traverse:
1. A race condition, where the renderer sends a navigation API key
   that is no longer in the joint session history.
2. When the traverse is initiated by a sandboxed iframe, and
   navigating to the given key would require navigating a frame
   that it is not permitted to navigate.

Notifying the renderer for (1) is trivial. For (2), we need to
plumb the key and the frame that initiated the traverse all the way
to NavigationControllerImpl::NavigateToExistingPendingEntry(), where
the sandboxed frame check occurs.

If we pass a RenderFrameHostImpl* all the way there, this allows us
to simplify other state that is passed to
NavigateToExistingPendingEntry(). Currently we need to pass the
sandboxed FTN id, and a bit for whether the navigation is browser
initiated. Now, a nullptr RenderFrameHostImpl* param indicates a
browser-initiated navigation, and NavigateToExistingPendingEntry()
can do the sandbox check directly with the RenderFrameHostImpl*.

This causes us to pass the following WPT tests, which were previously
skipped because they hung:
external/wpt/navigation-api/navigation-methods/sandboxing-back-parent.html
external/wpt/navigation-api/navigation-methods/sandboxing-back-sibling.html

It also allows us to remove the wpt_internal/ variants of those
tests, which existed only to give us test coverage of our
current behavior:
wpt_internal/navigation-api/sandboxing-back-parent-never-settles.html
wpt_internal/navigation-api/sandboxing-back-sibling-never-settles.html


Fixed: 1311786
Change-Id: I0a5e88c0123cd20dc6e312896aa2b049713669f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3902543
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Commit-Queue: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1051453}