[MPArch] Remove RenderFrameHostManager BrowsingContextState

As part of the in-place implementation of the new
BrowsingContextState, RenderFrameHostManager temporarily stored
a BrowsingContextState object. This patch removes the object
from RenderFrameHostManager, instead retrieving it from the
appropriate RenderFrameHost.

In legacy mode, the BrowsingContextState is coupled 1-1 with the
FrameTreeNode; however, in the new implementation,
BrowsingContextState needs to exist independently of FrameTreeNode.
This impacts things like how the replication state is accessed -
it is only available now when a RenderFrameHost exists.

Bug: 1270671
Change-Id: I300cad6e359bba2c7ade0742665b44cd9e73a663
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3379154


Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Rakina Zata Amni <rakina@chromium.org>
Commit-Queue: Harkiran Bolaria <hbolaria@google.com>
Cr-Commit-Position: refs/heads/main@{#979731}