config: add cgroup memory limit config

src/apprt/gtk/cgroup.zig

@@ -57,10 +57,11 @@ pub fn init(app: *App) ![]const u8 {
     // of "max" because it's a soft limit that can be exceeded and
     // can be monitored by things like systemd-oomd to kill if needed,
     // versus an instant hard kill.
-    // try internal_os.cgroup.configureMemoryLimit(transient, .{
-    //     // 1GB
-    //     .high = 1 * 1024 * 1024 * 1024,
-    // });
+    if (app.config.@"linux-cgroup-memory-limit") |limit| {
+        try internal_os.cgroup.configureMemoryLimit(transient, .{
+            .high = limit,
+        });
+    }
 
     return transient;
 }