Add embedded static editor support

[erseco]

This PR keeps the embedded static editor work and also updates the build/release flow: the editor is now fetched dynamically, built into the plugin, and packaged through the new Makefile and GitHub Actions workflows.

@pabloamayab I accidentally closed the previous PR #24 when I did a force-push to clean up the history, so I opened this new one.

I’ve also addressed the issues you reported in the previous PR. Could you please check this one again when you have a moment?

To test the embedded editor on the server, you need to run:

make build-editor
make up

Thanks.

[ignaciogros]

Thank you for this great tool, @erseco.

I've been testing with Moodle 4.5.10 using the static editor.

If you add a new activity an click on "Save and display" you go to the activity page, in which you can see the default content. I was expecting to go to eXe to create a new one.

Apart from that, just two details:

The "Edit with eXeLearning buttons" work, but:

• They're visible even when Moodle's "Edit mode" is off.
• The button's too close to the top of the screen when the viewer's full-screen mode's on.

[ignaciogros]

I suggest creating a new branch for this and integrating the development into this repository as soon as possible, so it's easier to contribute.

Thanks for the review.

About “Save and display”, this currently follows Moodle’s usual flow: the activity is created first and then its page is shown. We could make it open eXe directly after saving, but that would require an extra refresh/redirect.

It is also the same flow used when uploading an .elpx, so changing it only for this case would feel a bit inconsistent. I think it is better to keep it as is, even if it means one extra click.