Update script documentation removed files on startup

[Hilderin]

This PR is a prerequisite for #95821

It will adds the removed files in update_script_paths_documentation on first scan by comparing the file cache with the files on disk. It's important for #95821 so the removed scripts could be removed from the documentation.

Currently, update_script_paths_documentation does not remove documentation if the file does not exists on disk it will be implemented in #95821.

I tested with a project that has 3000 scripts files. After removing the files while the editor is closed and starting it, the method EditorFileSystem::_process_removed_files_first_scan tooks 22ms to find the 3000 missing scripts.

This is a team work with @anvilfolk

[anvilfolk]

The code makes sense to me. I'd like to see an added comment but it isn't critical! :)

Thanks for putting this together so fast!

[anvilfolk]

Actually, I just noticed there's a function called EditorFileSystem::update_files() which may be used for this purpose. It already does something very similar to what we need:

if (!FileAccess::exists(file)) {
	//was removed
	_delete_internal_files(file);
	if (cpos != -1) { // Might've never been part of the editor file system (*.* files deleted in Open dialog).
		...
		if (ClassDB::is_parent_class(fs->files[cpos]->type, SNAME("Script"))) {
			_queue_update_script_class(file, fs->files[cpos]->type, "", "", ""); ///////////// This here might regen docs?
			if (!fs->files[cpos]->script_class_icon_path.is_empty()) {
				update_files_icon_cache = true;
			}
		}

Perhaps it is worth collecting all the script files in a Vector and call this function instead. Would that work?

[Hilderin]

This method skip files that are not in the FileSystem because of the if (!_find_file(file, &fs, cpos)) {.
Also, the problem calling that method directly is that we try to avoid processing files while scanning. That's why I queued the documentation to be updated in update_script_paths_documentation which is processed after the scan. In the PR #93064, that should be merge soon, I added a progress bar to give feedback to the user while updating the documentation.

[anvilfolk]

You know best! I just noticed the method and thought it might be relevant! Exciting about the progress bar too! :)

[akien-mga]

Thanks!