There will be one more follow up commit to this, that will
add support for editing memberships of user groups and will
complete preliminary version for user group edit settings.
Follw up for #22214.
This is preparatory commit that does basic UI set up for
user group edit in group settings overlay. This allows us to
write proper hashchange logic for user group settings overlay
under diffrent situations.
The work in this commit will be extended in further commits
to add proper UI and group edit logic.
Anders Kaseorg
Purushottam Tiwari