Closes CLO-339

This PR moves the organization menu items inside the user menu, instead
of a standalone button within the title bar. We did it so because 1)
we're not fully sure how useful _always_ seeing in which org you are in
will be, and 2) seeing in which org you're in and seeing in which _plan_
you are in are very similar in terms of use case, and we don't currently
display the plan in the title bar... thus, that served as argument for
the same level of visibility.

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- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- N/A

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Co-authored-by: Gaauwe Rombouts <mail@grombouts.nl>