Navigation Editor: Handling saving for multiple menus

[Mamaduka]

What problem does this address?

Step 3 from #30322.

Currently, you can save one menu at a time.

What is your proposed solution?

A. Allow users to save multiple menus, like multi-entity saving of Reusable Blocks in post editor or Template Parts in the site editor.
B. Add warning dialog with confirmation when switching menus or creating a new one, and there are unsaved changes.

[getdave]

Noting here for the purpose of prioritisation that multi-saving of menus is not currently supported by the existing Navigation screen either. You must Save before you switch to editing another menu else your changes are lost.

[spacedmonkey]

It is worth nothing, that there are menu and menu items, which are stored differently here. Do you mean saving multiple menu items at the same time. It is worth noting that menu items already supports batched rest api requests. Menus do not currently support saving multiple menus in batch requests, but we could enable this functionality.

[Thelmachido]

Closing this issue due to the Navigation Screen project being moved to an inactive status on the feature projects page in coordination with the project leads.

If this work is picked back up, issues can be revisited and reopened as needed. Thanks for testing this early feature and giving feedback so the wider WordPress project could benefit from the lessons learned!