Generate menu items using plugins

Updating issue summary to make it easier to understand what the issue does, so we can get reviewers easier.

Code-wise, I don't have enough module experience to approve but functionality-wise, this is looking great!

Can you bring this up to date with 1.x now that #3386509: Refactor JavaScript is merged?

Looking good. Did a code review. See MR comments

Currently working on the templates here to ensure strings are translated, markup and aria attributes are correct.

The templates are in good shape now. There's a number of @todo's that we can get to later.

Still needs PHP and functionality reviews.

Note that when tried to test this, I ran into an error

The website encountered an unexpected error. Please try again later.

Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException: You have requested a non-existent service "plugin.manager.navigation_section_manager". Did you mean this: "plugin.manager.navigation_plugin_manager"? in Drupal\Component\DependencyInjection\Container->get() (line 157 of core/lib/Drupal/Component/DependencyInjection/Container.php).

I resolved this by ) checking out a previous version of the code (7db614c10cb472347875141e19d239cbe2df5624), 2) uninstalling the module, 3) checking out the latest version of the code, and 4) reinstalling the module.

After following the steps @mherchel mentioned in #22 (because I got the same error) I've been able to test this and feature wise works as expected.

Thanks for the reviews @deviantintegral and @tedbow!

What's the next step here? Should these be followups, or does this issue still need work?

Had discussions with @deviantintegral and @tedbow at https://drupal.slack.com/archives/C7AB68LJV/p1695052420501349.

Both of them are confused on where the data is coming from.

From @tedbow

I am little confused about the purpose of this issue vs using the menu system. It sort of uses the menu system, as in NavigationAdmin uses a menu but NavigationUser does not. Eventually will these all use menus? If so couldn’t you have just as much control over the markup by just having specific templates for these menu rather than just introducing the new NavigationSection concept
does 'base hook' => 'menu', mean that all the theme process stuff will still apply to these navigation sections also? (edited)

from @deviantintegral

I was also a little confused about this, but assumed I'd just missed prior context. The big thing I see is that I could see modules adding items to navigation sections that aren't menus, but some other UI widget. Like I think environment indicator is a good example of that? But I also think until we start wanting to create releases there isn't much harm in merging the MR, given that it's less hardcoded than the current code.

For now I'm committing this (so it can unblock some work on the templates and CSS). I'm adding this additional comments and info to #3381754: [PLAN] Use Menus to generate the links in the sidebar, where we can figure out how we want to get this data.

Thanks everyone!