Hide format filter and column for system projects

System projects like _pypi only contain packages of one format,
so the format filter dropdown and column are redundant.

frontend/src/pages/ProjectPage.tsx

@@ -294,6 +294,7 @@ function ProjectPage() {
           placeholder="Filter packages..."
           className="list-controls__search"
         />
+        {!project?.is_system && (
           <select
             className="list-controls__select"
             value={format}
@@ -306,6 +307,7 @@ function ProjectPage() {
               </option>
             ))}
           </select>
+        )}
       </div>
 
       {hasActiveFilters && (
@@ -341,11 +343,11 @@ function ProjectPage() {
               className: 'cell-description',
               render: (pkg) => pkg.description || '—',
             },
-            {
+            ...(!project?.is_system ? [{
               key: 'format',
               header: 'Format',
-              render: (pkg) => <Badge variant="default">{pkg.format}</Badge>,
-            },
+              render: (pkg: Package) => <Badge variant="default">{pkg.format}</Badge>,
+            }] : []),
             {
               key: 'tag_count',
               header: 'Tags',