Same permissions to release projecs as to acquire them

If only project managers are allowed to assign projects to orgs, then
only project managers should be allowed to remove projects from orgs.

backend/LexBoxApi/GraphQL/OrgMutations.cs

@@ -99,6 +99,7 @@ public async Task<IQueryable<Organization>> ReleaseProject(
             .Include(p => p.Organizations)
             .SingleOrDefaultAsync();
         NotFoundException.ThrowIfNull(project);
+        permissionService.AssertCanManageProject(projectId);
         var foundOrg = project.Organizations.FirstOrDefault(o => o.Id == orgId);
         if (foundOrg is not null)
         {