Keyboard shortcuts: fix warnings and add one for focusing chat input

[ellisonbg]

A few minor issues with keyboard shortcuts with Jupyter AI 3.0.0a0 pre-release.

Description

First, I see the following warnings in the browser console when using Jupyter AI 3.0.0a0 pre-release:

Second, when I have a chat document open and active, pressing enter doesn't focus the text box like I would expect.

Reproduce

1. Open chat document.
2. Make sure the text box is blurred, while the document is active.
3. Press enter to focus the text box.
4. See that it doesn't get focus (mouse click is required).

Expected behavior

• As a user, I want to use enter to focus the text box of a chat document.

[brichet]

Thanks for opening this.
I opened jupyterlab/jupyter-ai#1186 in jupyter-ai to fix the warning and the shortcut.

About the second issue, on my side I can type in the input box without pressing enter or using the mouse. Focusing it with the tabulation is enough to be able to type in it. Do you think that it should be handled differently ?

[dlqqq]

@brichet Thanks for opening that PR, I've merged it. Doesn't Ctrl + Shift + 1 focus the chat input like it did in Jupyter AI v2?

For reference, this is the shortcut being removed. If this was duplicated by Jupyter Chat, then it seems to imply that Ctrl + Shift + 1 also focuses the chat input.

  "jupyter.lab.shortcuts": [
    {
      "command": "jupyter-ai:focus-chat-input",
      "keys": ["Accel Shift 1"],
      "selector": "body",
      "preventDefault": false
    }
  ],

[brichet]

Indeed, this shortcut was duplicated in jupyter-chat, this is why there were the warnings when using with jupyter-ai.

In jupyter-chat, this is a little trickier, as there may be several open chats, so we use a WidgetTracker to focus on the current (last-used) chat. But that tracker only tracks the main area chats (#130), so the chats in the side panel can't be focused (neither to be restored, btw).

I opened #146 to fix it.