[Shared Tab Group] Add collaboration service framework

This CL adds the core framework for the CollaborationService, and the
interfaces needed for cross platform implementation.

Design doc: https://docs.google.com/document/d/1VMeQQu4rPj0zh2c3jvLpbKpd_6lzWO1HpRmXeEw_lXU/edit?usp=sharing&resourcekey=0-OHidXQLZlzoMPxb57ePF-w

Bug: 373403973
Change-Id: I42d7947436ea06ff3f44559b80eb208c9ec7cc59
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5937585
Commit-Queue: Hailey Wang <haileywang@google.com>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Siddhartha S <ssid@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1371681}