chore: register stimulus controllers from plugins

[adrianthedev]

Description

This PR adds the ability to auto-register StimulusJS controllers from plugins.
See how https://github.com/avo-hq/marksmith is achieving that.

This PR:

• adds the ability to register Stimulus controllers in plugins with Avo.asset_manager.register_stimulus_controller "marksmith", "MarksmithController"
• the controllers are outputted to a special window.Avo object
• there's a new late-registration file which picks them up and registers them in the current application
• the Stimulus Controller class is being assigned to the window object so it can be used by the plugin controllers in order to not bundle it with the plugin resulting in duplicated code (StimulusJS)

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

Screenshots & recording

Manual review steps

1. Install https://github.com/avo-hq/marksmith
2. Observe how it auto-registers the controllers and the JS works out of the box.

Manual reviewer: please leave a comment with output from the test if that's the case.

[codeclimate]

Code Climate has analyzed commit 98fd9ed and detected 0 issues on this pull request.

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[github-actions]

This PR has been merged into main. The functionality will be available in the next release.

Please check the release guide for more information.

[xeron]

@adrianthedev I'm getting this error after avo update:

11:12:06 web.1  | ActionView::Template::Error (Asset `late-registration.js` was not declared to be precompiled in production.
11:12:06 web.1  | Declare links to your assets in `app/assets/config/manifest.js`.
11:12:06 web.1  |
11:12:06 web.1  |   //= link late-registration.js
11:12:06 web.1  |
11:12:06 web.1  | and restart your server):
11:12:06 web.1  |
11:12:06 web.1  | Causes:
11:12:06 web.1  | Sprockets::Rails::Helper::AssetNotPrecompiledError (Asset `late-registration.js` was not declared to be precompiled in production.
11:12:06 web.1  | Declare links to your assets in `app/assets/config/manifest.js`.

[adrianthedev]

Please downgrade for now. We'll come out with a hotfix soon

[Paul-Bob]

@xeron this issue was fixed and released on 3.16.4