Allow adding custom export platforms using scripts / GDExtension.

[bruvzg]

Adds option to make custom export platforms using scripts or GDExtension without editor rebuild.

TODO:

• Docs.
• GDExtension sample project - https://github.com/bruvzg/gdextension_editor_export_platform_template
• Testing.
• Expose optional helper methods from base EditorExportPlatform (zip / pck creation, finding export template, ssh/scp methods).
• Expose generic ExportPreset properties.

[dsnopek]

Thanks for taking this on! I started a local branch with the same goal back in January, but just haven't had the time to finish it up. Your version is already further along than mine :-)

[m4gr3d]

Have yet to test it but the logic looks good.

[raulsntos]

I tested this with the C# ExportPlugin to implement the C# changes from my superseded PRs (raulsntos@c069790) and works great.

I don't understand the changes to expose ScriptEditor::get_breakpoints, it seems unrelated. Is this needed for scripts implementing export platforms?

Also, since EditorExportPlugin has no way to make the export process fail, my superseded PR (#90555) was relying on checking if there were any error messages added to determine if the export failed. Something like this:

diff --git a/editor/export/editor_export_platform.cpp b/editor/export/editor_export_platform.cpp
index eb9e9b9adf..53d6d689a1 100644
--- a/editor/export/editor_export_platform.cpp
+++ b/editor/export/editor_export_platform.cpp
@@ -71,7 +71,7 @@ bool EditorExportPlatform::fill_log_messages(RichTextLabel *p_log, Error p_err)
 	p_log->add_text(" ");
 	p_log->add_text(get_name());
 	p_log->add_text(" - ");
-	if (p_err == OK) {
+	if (p_err == OK && get_worst_message_type() < EditorExportPlatform::EXPORT_MESSAGE_ERROR) {
 		if (get_worst_message_type() >= EditorExportPlatform::EXPORT_MESSAGE_WARNING) {
 			p_log->add_image(p_log->get_editor_theme_icon(SNAME("StatusWarning")), 16 * EDSCALE, 16 * EDSCALE, Color(1.0, 1.0, 1.0), INLINE_ALIGNMENT_CENTER);
 			p_log->add_text(" ");

Otherwise, an ExportPlugin can add error messages but the export log dialog will show Completed with warnings:

[bruvzg]

Also, since EditorExportPlugin has no way to make the export process fail, my superseded PR (#90555) was relying on checking if there were any error messages added to determine if the export failed. Something like this

Added it.

I don't understand the changes to expose ScriptEditor::get_breakpoints, it seems unrelated. Is this needed for scripts implementing export platforms?

It might be necessary if you want to implement custom one click deploy for the platform with remote debugging support. Usually the list of breakpoints is passed to the remote executable with --breakpoints argument, and handled by gen_export_flags, but for some platforms you can't just pass command line arguments.

[dsnopek]

Thanks for your epic work on this! It's looking really great :-)

I haven't tested it, but all the important code looks good to me - I just have two little notes.