Investigate top nav "Menu" dropdown
## Problem
Right now it can be confusing as to what the "Menu" text in the top bar means in relation to what is inside and in contrast to the other menus (top and left). This menu has become a catch-all for different types of content.

The items within the `Menu` dropdown contain personal objects (snippets) as well as global entities (milestones, environments, operations, security), and a mixture of both (activity, projects, groups).
Because of the mixture of content, its difficult to know who these dashboards are for and how they should be used. Additionally, they are duplicated in individual groups/projects.
## Next steps
As gitlab~21094730 just took over the ~"Category:Navigation & Settings", we should research the reasons behind why the `Menu` dropdown uses this label, as well as determine if there is a better IA for this content that groups related content in a reliable and consistent way.
### Initial Research
- [x] [Research the current decision to use the word "Menu"](https://gitlab.com/gitlab-org/gitlab/-/issues/359382#note_915598936)
- [x] [Decide if there might be an alternate label](https://gitlab.com/gitlab-org/gitlab/-/issues/359382#note_919792733)
### Solution Design + Validation (1st Iteration)
- [x] Explore ideas for alternative ideas → https://gitlab.com/gitlab-org/gitlab/-/issues/362396
- [x] Validate solution → https://gitlab.com/gitlab-org/gitlab/-/issues/362536
### Solution Design + Validation (2nd Iteration)
- [ ] Refinement for menu menu alternatives → https://gitlab.com/gitlab-org/gitlab/-/issues/366082
- [ ] Validate solution → https://gitlab.com/gitlab-org/ux-research/-/issues/2006
epic