[Feat] Create a new classic menu block

[ashiishme]

Is your feature request related to a problem? Please describe.
This is a new request to make the menu items & blocks management separate & easier in navigation block.

Describe the solution you'd like

Current proposed solution based on the @draganescu thoughts:

A classic menu block in navigation block ( child ) that would remove the tie between the navigation block and classic menu-items in the navigation screen.
The idea is to delegate all management of block <-> walker <-> db items to another block, not to navigation.

Describe alternatives you've considered
Not yet. Please propose your ideas in comment.

check the discussion about this feature in slack.

[noisysocks]

I could see this living alongside the Pages block (#23689) so that, after inserting a (empty) Navigation block, the user has a choice to:

1. Insert a Link and start the menu from scratch; or
2. Insert a Pages block which populates the navigation with all the site's pages; or
3. Insert a Menu block which populates the navigation with an existing site's menu.

See #23207.

[noisysocks]

Closing this for now as it doesn't fit in with the planned approached outlined in #24364. We can re-open if things change.