Adds `want_advertise_in_communities_directory` to the realm model
to track organizations that give permission to be listed on such
a site / directory on zulip.com.
Adds a checkbox to the organization profile admin for
organizations to give permission to be advertised in the
Zulip communities directory.
Adds a help center article about the Zulip communities directory
and uses a shared intro documentation file to create sections in
the articles on creating an organization profile and moderating
open organizations.
Co-authored-by: Alya Abbott <alya@zulip.com>
This renames references to user avatars, bot avatars, or organization
icons to profile pictures. The string in the UI are updated,
in addition to the help files, comments, and documentation. Actual
variable/function names, changelog entries, routes, and s3 buckets are
left as-is in order to avoid introducing bugs.
Fixes#11824.