Support Godot 4.7 import pipeline

[endaye]

Summary

This updates the TexturePacker spritesheet importer for Godot 4.7 compatibility.

Changes:

• Import sheet image dependencies with append_import_external_resource() before loading them.
• Load imported textures with ResourceLoader.CACHE_MODE_REPLACE_DEEP.
• Add a fallback return value to _get_preset_name() so the importer script compiles under Godot 4.7.
• Guard recursive .tres cleanup against missing directories.

Why

In Godot 4.7, the custom .tpsheet importer can run before dependent image textures are imported and available through ResourceLoader.load(). Calling append_import_external_resource() during _import() lets Godot import and track those image dependencies before atlas resources are generated.

Godot 4.7 also reports _get_preset_name() as a parse error when not all code paths return a value.

Validation

Tested with Godot 4.7.stable.steam.5b4e0cb0f using a temporary project containing:

• the plugin
• a minimal PNG sheet
• a minimal .tpsheet

Command:

godot4 --headless --editor --quit --path /private/tmp/tp-godot-47-test