Core: Avoid including modules/modules_enabled.gen.h in headers

[Repiteo]

• Alternative to SCons: Separate module defines #99302

Because modules/modules_enabled.gen.h regenerates anytime a module is changed, this causes all files with this header to necessitate a rebuild. For definition files this is generally fine, but header files can cause cascading recompilations across dozens, if not hundreds, of unnecessary files. Taking the test format from #99302, the refactors from this PR resulted in:

Results

scons: Building targets ...
[  4%] Generating modules\modules_enabled.gen.h ...
[ 79%] Compiling editor\editor_node.cpp ...
[ 79%] Generating modules\register_module_types.gen.cpp ...
[ 79%] Generating modules\modules_tests.gen.h ...
[ 79%] Compiling modules\register_module_types.gen.cpp ...
[ 79%] Compiling tests\test_main.cpp ...
[ 79%] Compiling modules\navigation\3d\nav_mesh_generator_3d.cpp ...
[ 79%] Compiling editor\scene_tree_dock.cpp ...
[ 79%] Compiling modules\gdscript\language_server\gdscript_workspace.cpp ...
[ 79%] Compiling editor\themes\editor_icons.cpp ...
[ 79%] Compiling platform\windows\export\export_plugin.cpp ...
[ 79%] Compiling modules\gdscript\language_server\gdscript_language_protocol.cpp ...
[ 79%] Compiling scene\theme\default_theme.cpp ...
[ 79%] Compiling platform\macos\export\export_plugin.cpp ...
[ 79%] Compiling scene\gui\rich_text_label.cpp ...
[ 79%] Compiling platform\web\export\export_plugin.cpp ...
[ 79%] Compiling modules\text_server_fb\register_types.cpp ...
[ 79%] Compiling modules\text_server_adv\thorvg_svg_in_ot.cpp ...
[ 79%] Compiling editor\export\codesign.cpp ...
[ 79%] Compiling editor\plugins\bone_map_editor_plugin.cpp ...
[ 79%] Compiling modules\gdscript\language_server\gdscript_language_server.cpp ...
[ 79%] Compiling platform\ios\export\export_plugin.cpp ...
[ 79%] Compiling modules\gdscript\language_server\gdscript_extend_parser.cpp ...
[ 79%] Compiling modules\navigation\3d\godot_navigation_server_3d.cpp ...
[ 79%] Compiling editor\project_converter_3_to_4.cpp ...
[ 79%] Compiling main\main.cpp ...
[ 79%] Compiling scene\resources\shader.cpp ...
[ 79%] Compiling platform\android\export\export_plugin.cpp ...
[ 79%] Compiling editor\rename_dialog.cpp ...
[ 79%] Compiling editor\editor_help.cpp ...
[ 79%] Compiling modules\gdscript\language_server\gdscript_text_document.cpp ...
[ 79%] Compiling editor\doc_tools.cpp ...
[ 80%] Compiling platform\linuxbsd\export\export_plugin.cpp ...
[ 80%] Compiling modules\gltf\gltf_document.cpp ...
[ 80%] Linking Static Library modules\modules.windows.editor.dev.x86_64.lib ...
[ 80%] Compiling modules\text_server_adv\register_types.cpp ...
[ 80%] Compiling editor\import\resource_importer_dynamic_font.cpp ...
[ 80%] Compiling modules\text_server_adv\text_server_adv.cpp ...
[ 80%] Compiling editor\register_editor_types.cpp ...
[ 80%] Compiling core\io\logger.cpp ...
[ 80%] Compiling modules\text_server_fb\text_server_fb.cpp ...
[ 80%] Compiling modules\gdscript\register_types.cpp ...
[ 80%] Compiling core\config\project_settings.cpp ...
[ 80%] Compiling modules\text_server_fb\thorvg_svg_in_ot.cpp ...
[ 80%] Linking Static Library modules\module_navigation.windows.editor.dev.x86_64.lib ...
[ 81%] Linking Static Library scene\scene.windows.editor.dev.x86_64.lib ...
[ 85%] Linking Static Library core\core.windows.editor.dev.x86_64.lib ...
[ 85%] Linking Static Library modules\module_gltf.windows.editor.dev.x86_64.lib ...
[ 88%] Linking Static Library main\main.windows.editor.dev.x86_64.lib ...
[ 88%] Linking Static Library modules\module_text_server_fb.windows.editor.dev.x86_64.lib ...
[ 89%] Linking Static Library modules\module_gdscript.windows.editor.dev.x86_64.lib ...
[ 92%] Linking Static Library modules\module_text_server_adv.windows.editor.dev.x86_64.lib ...
[ 97%] Building compilation database compile_commands.json
[ 99%] Linking Static Library editor\editor.windows.editor.dev.x86_64.lib ...
[100%] Building node count database .scons_node_count
[100%] Linking Static Library tests\tests.windows.editor.dev.x86_64.lib ...
[100%] Linking Program bin\godot.windows.editor.dev.x86_64.exe ...
[100%] Linking Program bin\godot.windows.editor.dev.x86_64.console.exe ...
[100%] scons: done building targets.
[Time elapsed: 00:01:00.56]

So while this doesn't reach the peak speed of #99302's implementation, those speeds were only possible by fundamentally changing how modules were parsed. Not only does this PR leave the module logic itself entirely untouched, but it does so while improving compile time threefold!

[akien-mga]

Looks good to me.