Fixes additional compatibility issues found when building against Godot 4.5:
1. String::parse_utf8() deprecated and removed in Godot 4.5
- Replaced with String::utf8() for Godot 4.5+
- Added version guards to maintain compatibility with older versions
- Affected files: SpineAnimation, SpineAnimationTrack, SpineAtlasResource,
SpineAttachment, SpineBoneData, SpineConstraintData, SpineEventData,
SpineSkeletonDataResource, SpineSkin, SpineSlotData, SpineSprite
2. Editor header file locations changed in Godot 4.5
- editor/editor_file_system.h -> editor/file_system/editor_file_system.h
- editor/plugins/animation_*_editor_plugin.h -> editor/animation/animation_*_editor_plugin.h
- Added version guards for correct include paths
- Affected files: SpineAtlasResource, SpineAnimationTrack
These changes ensure spine-godot builds successfully with both Godot 4.5 and earlier versions.
