Fix adding a translation CSV results in errors on initial import for many types of resources

[Hilderin]

Fixes #93704

@mihe was right, #92320 did not fix the problem. In fact, there were two problems with CSV importation, and #92320 solved only one of them.

The remaining problem was caused by the creation of the translation file in res://, which triggered update_files and then _update_pending_scene_groups. This caused _update_pending_scene_groups to load all the scenes during the first scan before all the resources were imported. On the first scan, without the .godot folder, all the scenes are processed. _update_pending_scene_groups must be called after all resources are loaded.

At first, I tested only adding !first_scan condition before _process_update_pending. It worked when starting the MRP project without the .godot folder. But if I started an empty project and pasted the CSV file and a scene with resources at the same time, the same problem occurred. So the fix is to never call _process_update_pending while scanning. Anway, it should be called at the end of the scanning, once all the resources are loaded.

Note: I think #93723 could also fix this problem because with these modifications, scene are not loaded anymore to find the groups.

Tested with the MRP from #93704 and #83200.

[mihe]

I can confirm that this does fix #93704, and as far as I can tell _process_update_pending and the filesystem_changed signal are both called once the importing is finished, so the change looks reasonable, assuming _update_file_icon_path isn't dependent on either of them in some weird way.

[akien-mga]

Looks good to me overall, and doesn't seem to introduce regressions in some quick testing on projects with CSV translations.

[KoBeWi]

Suggested change

	call_deferred(SNAME("emit_signal"), "filesystem_changed"); //update later
	call_deferred(SNAME("emit_signal"), "filesystem_changed"); // Update later.

[akien-mga]

Forgot about this before merging. That will be for the next PR in that code :D

[akien-mga]

Thanks!