Add page handler and resources for Related Website Sets DevUI

Add WebUI controller and reference to resources directory for
related-website-sets.
Add routing for chrome://privacy-sandbox-internals/related-website-sets

Bug: 330877132
Change-Id: I4d35273570a68d79ea5cf9d08a6c229039533b65
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5593094


Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Gabriel Tellez Ornelas <gtellezornelas@google.com>
Reviewed-by: Dylan Cutler <dylancutler@google.com>
Cr-Commit-Position: refs/heads/main@{#1312764}