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>

routers/api/v1/org/org.go

@@ -225,8 +225,8 @@ func Get(ctx *context.APIContext) {
 	//   "200":
 	//     "$ref": "#/responses/Organization"
 
-	if !models.HasOrgVisible(ctx.Org.Organization, ctx.User) {
-		ctx.NotFound("HasOrgVisible", nil)
+	if !models.HasOrgOrUserVisible(ctx.Org.Organization, ctx.User) {
+		ctx.NotFound("HasOrgOrUserVisible", nil)
 		return
 	}
 	ctx.JSON(http.StatusOK, convert.ToOrganization(ctx.Org.Organization))