Fix slow editor load on large projects

[Hilderin]

• Fixes partially Editor takes a long time to load project with large amount of media files #94917

I tested a project with all the image from https://github.com/PMDCollab/SpriteCollab/tree/master/sprite which contains 61332 png.

Problem found:

• In the new EditorFileSystem::_first_scan_process_scripts, the method ResourceLoader::get_resource_type was called on each file and this method loops on all the loader and calls get_resource_type which for some loader read the resource file. So all files were read multiple times.

Before this PR:

• First scan (before Filesystem Dock progress bar appears): 1 min

After this PR:

• First scan (before Filesystem Dock progress bar appears): 4-5 sec.

I found another performance problem with EditorFileSystem::_test_for_reimport but that will take more modifications to fix, I'll create another PR later.

[Jordyfel]

It is possible to get all valid script extensions from ScriptServer. Something like

for (int i = 0; i < ScriptServer::get_language_count(); i++) {
	ScriptServer::get_language(i)->get_extension();
}

[smix8]

Great! Can confirm this makes the scanning files dialog appear near instant on a 100.000+ files project.

It still does the kinda ridiculous reloading from disk for all the files in a project on a file change / rename but I guess that is the other issue mentioned with the EditorFileSystem::_test_for_reimport?

[Hilderin]

It is possible to get all valid script extensions from ScriptServer. Something like

for (int i = 0; i < ScriptServer::get_language_count(); i++) {
	ScriptServer::get_language(i)->get_extension();
}

Thanks @Jordyfel, I did not thought about it. It even faster, I'm down to 1-3 seconds for the first scan on the same project instead of 4-5 seconds. I pushed the modifications to use your suggestion.

[Hilderin]

Great! Can confirm this makes the scanning files dialog appear near instant on a 100.000+ files project.

Nice!!! Thanks to test it.

It still does the kinda ridiculous reloading from disk for all the files in a project on a file change / rename but I guess that is the other issue mentioned with the EditorFileSystem::_test_for_reimport?

Exactly, each .import file are read like 3 times on editor load. I'm looking into it. Pretty sure I will not be able to do miracles but I'll do my best.

[Hilderin]

I'm closing this PR since the V2 has been approved.