linux: Forward ctrl-w/ctrl-e to terminal (#13263)

This fixes `ctrl-w` and `ctrl-e` not working in the terminal pane but
instead triggering Zed actions ("close pane" and "search project files"
respectively).

I've added both because I think they're pretty commonly used in
terminals, since they're default Emacs-style keybindings.

But I also didn't want to add more, since it's relatively easy for users
to define themselves which keybindings should be forwarded to the
terminal and which not.

All that's required is adding something like this to the keymap:

```json
{
  "context": "Terminal",
  "bindings": {
    "ctrl-n": ["terminal::SendKeystroke", "ctrl-n"],
    "ctrl-p": ["terminal::SendKeystroke", "ctrl-p"]
  }
}
```
cc @mikayla-maki 

Release Notes:

- N/A

assets/keymaps/default-linux.json

@@ -296,6 +296,13 @@
       "ctrl-alt-shift-x": "search::ToggleRegex"
     }
   },
+  {
+    "context": "Terminal",
+    "bindings": {
+      "ctrl-w": ["terminal::SendKeystroke", "ctrl-w"],
+      "ctrl-e": ["terminal::SendKeystroke", "ctrl-e"]
+    }
+  },
   // Bindings from VS Code
   {
     "context": "Editor",