Fix GDExtension classes inheriting from Resource not using icons in FileSystem

[SaNeOr]

fix #97387

[Hilderin]

Sounds good to me! Tested with the MRP on master and with this PR and it fixes the issue as expected.

[akien-mga]

Thanks!

[akien-mga]

This seems to cause a crash in one of my test projects:

================================================================
handle_crash: Program crashed with signal 11
Engine version: Godot Engine v4.4.dev.custom_build (ac1ef5c9f64f1c21f9addfc98be460e08dff8fb7)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] /lib64/libc.so.6(+0x40d00) [0x7efce506ad00] (??:0)
[2] CowData<char32_t>::_ref(CowData<char32_t> const&) (/home/akien/Godot/godot/./core/templates/cowdata.h:461)
[3] String::String(String const&) (/home/akien/Godot/godot/./core/string/ustring.h:483)
[4] Resource::get_path() const (/home/akien/Godot/godot/./core/io/resource.cpp:95)
[5] EditorFileSystem::_update_file_icon_path(EditorFileSystemDirectory::FileInfo*) (/home/akien/Godot/godot/./editor/editor_file_system.cpp:1981 (discriminator 6))
[6] EditorFileSystem::_update_files_icon_path(EditorFileSystemDirectory*) (/home/akien/Godot/godot/./editor/editor_file_system.cpp:1995 (discriminator 3))
[7] EditorFileSystem::_update_files_icon_path(EditorFileSystemDirectory*) (/home/akien/Godot/godot/./editor/editor_file_system.cpp:1992 (discriminator 3))
[8] EditorFileSystem::_update_files_icon_path(EditorFileSystemDirectory*) (/home/akien/Godot/godot/./editor/editor_file_system.cpp:1992 (discriminator 3))
[9] EditorFileSystem::_update_files_icon_path(EditorFileSystemDirectory*) (/home/akien/Godot/godot/./editor/editor_file_system.cpp:1992 (discriminator 3))
[10] EditorFileSystem::_notification(int) (/home/akien/Godot/godot/./editor/editor_file_system.cpp:1672)
[11] EditorFileSystem::_notificationv(int, bool) (/home/akien/Godot/godot/./editor/editor_file_system.h:145 (discriminator 14))
[12] Object::notification(int, bool) (/home/akien/Godot/godot/./core/object/object.cpp:878)
[13] SceneTree::_process_group(SceneTree::ProcessGroup*, bool) (/home/akien/Godot/godot/./scene/main/scene_tree.cpp:1020)
[14] SceneTree::_process(bool) (/home/akien/Godot/godot/./scene/main/scene_tree.cpp:1092 (discriminator 2))
[15] SceneTree::process(double) (/home/akien/Godot/godot/./scene/main/scene_tree.cpp:582)
[16] Main::iteration() (/home/akien/Godot/godot/main/main.cpp:4383 (discriminator 3))
[17] OS_LinuxBSD::run() (/home/akien/Godot/godot/platform/linuxbsd/os_linuxbsd.cpp:962 (discriminator 1))
[18] /home/akien/Godot/godot/bin/godot.linuxbsd.editor.dev.x86_64(main+0x14b) [0x6098af1] (/home/akien/Godot/godot/platform/linuxbsd/godot_linuxbsd.cpp:85)
[19] /lib64/libc.so.6(+0x2a088) [0x7efce5054088] (??:0)
[20] /lib64/libc.so.6(__libc_start_main+0x8b) [0x7efce505414b] (??:0)
[21] /home/akien/Godot/godot/bin/godot.linuxbsd.editor.dev.x86_64(_start+0x25) [0x60988e5] (??:?)
-- END OF BACKTRACE --
================================================================

Trying to figure out why and make a MRP.

[akien-mga]

It's crashing for me when there's an .icns icon in the project:
new-test-project.zip

Edit: #97491 should fix it.

[akien-mga]

This is wrongly assuming that the result of EditorNode::get_singleton()->get_class_icon(file_info->type) is valid and can de-referenced.

[akien-mga]

Fixed by #97491.