Navigation Menu Widget missing from the block inserter for widgets/customize-widgets

[celloexpressions]

The legacy "Navigation Menu" widget is missing from the block-widget inserter in trunk. This widget allows users to select a menu, managing the menu contents on the menus screen or with the menus panel in the customizer. See several related open tickets for this widget such as #44665.

Presumably this can eventually be replaced with a navigation block. But for 5.8, and until the old menu system is completely replaced with blocks, the legacy menu widget needs to continue to work and be available to add to widget areas.

[andraganescu]

I added ​a PR upstream that makes the navigation menu widget accessible via the inserter in the block based widgets editor. I thiink it's the right call as the block implementation of the navigation is not yet syncing to the classic menus.

[noisysocks]

@andraganescu: We'll need to make this change in Core, not in the Gutenberg repo.

I also noticed that there is no block equivalent for the Meta widget. We should enable that, too.

[noisysocks]

In 51067:

Enable Meta and Nav Menu widgets in Legacy Widget block

Allows users to insert a Meta or Nav Menu widget using the Legacy Widget block,
as there is not yet a block equivalent for the Meta and Nav Menu widgets.

Fixes #53301.
Props celloexpressions, andraganescu.

[noisysocks]

In 51069:

Fix failing block editor test

Removes the Meta and Nav Menu widgets from the set of widgets expected by the
test for get_default_block_editor_settings().

Follows [51067].
See #53301.