Provide Config Action to add new blocks to navigation from recipes

First shot for this one.

It allows to provide a recipe like this:

name: Navigation Block Test Recipe
type: Examples
description: 'Adds a block to Navigation.'
install:
  - navigation
config:
  actions:
    navigation.block_layout:
      addNavigationBlock:
        position: 1
        configuration:
          id: 'navigation_menu:content'
          label: Content From Recipe
          label_display: 1
          provider: navigation
          level: 1
          depth: 2

After applying the recipe, a new block with the settings described above is added to the Navigation.

This one needs tests and some extra work, but let's open the discussion about it.

Thank you for bringing up that issue, I was unaware of it. Definitely avoid reinventing the wheel should be a priority.

Navigation use case might differ a bit, given that sections and regions are more limited than in other scenarios. I'm pretty sure we could take advantage of that trait, though.

This initial approach is a proof of concept to validate the approach. More than happy to readjust it to be based on the code in the mentioned issue once it is ready.

Thanks!

This will be probably necessary for Starshot.

Initial approach including base test coverage.

@m4olivei The way LB is implemented in Navigation, nested in a different config entity makes impossible to use the trait approach described in #3475115: Provide a Config Action to add a component in a layout.

We discovered it when I tried to apply it to this one. See comments #6 & #7 in #3475115: Provide a Config Action to add a component in a layout.

If we want to provide config actions for Navigation, with the tools we have today, it should be based on a custom plugin.

Thank you for your review. Feedback addressed.

Draft CR created.