feat(Navigation): emit dedicated event for loading additional entries

[blizzz]

Summary

Currently, apps that add custom/dynamic entries have to listen to the BeforeTemplateRenderedEvent when they intend to add navigation entries. This is already rather a hack and relies on template rendering.

But there is the endpoint of the NavigationController in core that offers to get the current data of the app navigation. The app management is making use of it, and Tables would like to do so too. But in this code path, the above mentioned Event is not being fired. Hence, fire a dedicated event.

This is a grey zone between a feature and a bug. For the other use case in tables we can work around it with an own endpoint, for the app management this can be considered a bug, and solving it would require the change to be backported. It would not be breaking. Since it is nowhere critical I am fine having it for 31 only.

Screenrecording of the problem:

Screencast_20241217_202733.webm

With this change and modified tables app:

Screencast_20241217_202922.webm

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[blizzz]

Adjusted and extended test, fixed another instantiation (in file`s App.php) and updated autoloader info.

I think the failing test is unrelated, but don't really know what live photo is.

[provokateurin]

Live photo also fails in other PRs atm, so unrelated indeed