Add Visible modes function from Organisation to Users too (#16069)

You can limit or hide organisations. This pull make it also posible for users

- new strings to translte
- add checkbox to user profile form
- add checkbox to admin user.edit form
- filter explore page user search
- filter api admin and public user searches
- allow admins view "hidden" users
- add app option DEFAULT_USER_VISIBILITY
- rewrite many files to use Visibility field
- check for teams intersection
- fix context output
- right fake 404 if not visible

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Andrew Thornton <art27@cantab.net>

modules/convert/user.go

@@ -62,10 +62,14 @@ func toUser(user *models.User, signed, authed bool) *api.User {
 		Following:    user.NumFollowing,
 		StarredRepos: user.NumStars,
 	}
+
+	result.Visibility = user.Visibility.String()
+
 	// hide primary email if API caller is anonymous or user keep email private
 	if signed && (!user.KeepEmailPrivate || authed) {
 		result.Email = user.Email
 	}
+
 	// only site admin will get these information and possibly user himself
 	if authed {
 		result.IsAdmin = user.IsAdmin