## Summary of the Pull Request
Changes the way the `useTabSwitcher` setting works. It now accepts either a boolean or a string:
* `true`, `"mru"`: Use the tab switcher with MRU tab switching
* `"inOrder"`: Use the tab switcher, with in-order tab switching
* `false`, `"disabled"`: Don't use the tab switcher. Tabs will switch in-order.
This is following the discussion chronicled in #8025, as well as the follow-up investigation in that thread.
## References
* #7952 introduced MRU tab switching
## PR Checklist
* [x] Closes#8025 - there's also discussion of using a parameter in an action to override this setting, but that should get punted to a follow-up task
* [x] I work here
* [x] Tests added/passed - YOU BET THEY WERE
* [ ] Requires documentation to be updated
## Validation Steps Performed
I've been switching tabs all day and all night, with different settings values, and hot-reloading the setting.
I also _ran the test_ I added.
6639df9edc