Update JetBrains keymap (#4243)

I want to immediately archive the `keymaps` repo tomorrow. This is the
only change that needs to be brought over.

Release Notes:

- N/A

assets/keymaps/jetbrains.json

@@ -79,5 +79,11 @@
       "cmd-1": "workspace::ToggleLeftDock",
       "cmd-6": "diagnostics::Deploy"
     }
+  },
+  {
+    "context": "ProjectPanel",
+    "bindings": {
+      "enter": "project_panel::Open"
+    }
   }
 ]