Calculate PublicOnly for org membership only once (#32234)

Refactoring of #32211

this move the PublicOnly() filter calcuation next to the DB querys and
let it be decided by the Doer

---
*Sponsored by Kithara Software GmbH*

(cherry picked from commit 43c252dfeaf9ab03c4db3e7ac5169bc0d69901ac)

Conflicts:
	models/organization/org_test.go
	models/organization/org_user_test.go
	routers/web/org/home.go

  rather simple conflict resolution but not trivial
  tests/integration/user_count_test.go had to be adapted (simple)
  because it does not exist in Gitea and uses the modified model

routers/web/org/home.go

@@ -110,10 +110,12 @@ func Home(ctx *context.Context) {
 	}
 
 	opts := &organization.FindOrgMembersOpts{
-		OrgID:       org.ID,
-		PublicOnly:  ctx.Org.PublicMemberOnly,
-		ListOptions: db.ListOptions{Page: 1, PageSize: 25},
+		Doer:         ctx.Doer,
+		OrgID:        org.ID,
+		IsDoerMember: ctx.Org.IsMember,
+		ListOptions:  db.ListOptions{Page: 1, PageSize: 25},
 	}
+
 	members, _, err := organization.FindOrgMembers(ctx, opts)
 	if err != nil {
 		ctx.ServerError("FindOrgMembers", err)