Simplify the global navigation to improve discoverability and usability
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## Problem to solve
Navigating GitLab, especially when it comes to distinguishing between Groups and Projects and wayfinding across larger instances, has consistently been highlighted as a pain point in [research](https://gitlab.com/gitlab-org/ux-research/-/issues/1178) and [SUS feedback](https://dovetailapp.com/extensions/3d166abc-9031-48a8-8ef8-741ed3c5ef79/tags/a91f8500-e328-4119-968c-aeee356ab623#v=ewAiAHEAIgA6ACIAIgB9AA) (Internal Dovetail link). There's also a lack of awareness of instance-level features and how they relate to those typically found at the Group and Project level.
## Proposal
Simplify the top navigation by consolidating the `Projects`, `Groups`, and `More` menus. While we're making changes to the menu, we should move toward a "Recently Visited" list for Projects and Groups for consistency and to avoid reliance on local browser storage and provide an area for actions and quick links like "Create new project".
## Details

## How will we know if we're successful?
1. Improve discoverability of menu options as measured through first-click testing and findability rate
1. Increased click-through to instance-level features from the menu
## Documentation
This effort will change the global navigation considerably. While the styling will remain consistent, any documentation entry that includes a screenshot of the global navigation should be updated. Any documentation that specifically addresses the `Projects` `Groups` or `More` menu will need to be updated. An issue in this epic will consolidate documentation changes to be deployed alongside the feature.
## What we'll do later
This epic doesn't include anything specifically addressing the `+` (New) button, though many of the actions currently contained in that menu could be incorporated into the design. We will iterate toward integration of those actions after we get feedback on the new menu.
## Iteration plan
**MVC**
- Combine Projects, Groups, and More into one menu https://gitlab.com/gitlab-org/gitlab/-/issues/301143
- Use "Recently visited" instead of "Frequently visited" for Projects & Groups https://gitlab.com/gitlab-org/gitlab/-/issues/301144
- Provide area for actions in consolidated menu https://gitlab.com/gitlab-org/gitlab/-/issues/300128
**Post-MVC**
- Improve search results for large instances and groups
- Update the styling and iconography in the menu
- Create tabs for starred Projects and Groups
epic