Improve the Onboarding Experience for Collab

[rgbkrk]

Check for existing issues

• [X] Completed

Describe the bug / provide steps to reproduce it

When trying to on board a new Zed user, this is roughly how the debugging flow ends up going:

1. Create a new private channel (or reuse an existing one)
2. Right click the channel, click Manage Members
3. Realize that I have to click Invite Members
4. Type their username in, it doesn't come up
5. Ask them if they've signed in
6. They say yes, so I send them the channel link
7. That takes them to zed.dev where they sign in
8. Add them via Invite Members this time for real
9. Ask them to open the collab panel or click the link
10. They click the link, which takes them to zed but without the channel open
11. Tell them how to open the collab panel directly
12. They are greeted with a checkbox they can click that doesn't do anything
13. Ask them to restart zed
14. Now they can open the channel
15. ...
16. At some point we want to screenshare, which requires a system settings change and another restart

A few areas I think this could be improved:

• Invite members should have some way to prompt for emailing someone to invite them (encourage network effects)
• The collab panel should have some amount of readiness test in advance of the pairing session, so that I can tell a colleague to run something that will help them through a flow. They would have done it in advance of our meeting if I said so.
• Figure out where the UI got stuck with the checkbox such that the collab panel wouldn't admit the new user

Environment

Zed: v0.157.0 (Zed Nightly 5377674fc05ff151750767d19a0026f28c8df67a) OS: macOS 14.6.1 Memory: 128 GiB Architecture: aarch64

If applicable, add mockups / screenshots to help explain present your vision of the feature

No response

If applicable, attach your Zed.log file to this issue.

No response