Allows you to click on the zoom percent to edit it. Right clicking the
percentage resets to 100%.

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [ ] 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)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- Added support for editing image viewer zoom levels directly from the
toolbar.

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Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>