Show shader editor on shader compilation error

[TheDying0fLight]

• Resolves Shader editor should be shown when shader compilation error is raised #35119

Goals:

• Remove printing the shader code to "Output"
• Fix initial shader compilation with incorrect path
• Show the shader editor on shader compilation error:
  • In editor
    • Without breaking encapsulation Show shader editor on shader compilation error #112954 (comment)
  • On editor startup
  • While running project

What I tested:

• Shader types:
  • Canvas item
  • Spatial
• Renderer:
  • Forward
  • Mobile
  • Compatibility

Note: I also edited _meta_clicked which is not directly related to the issue but I used that code for inspiration and found it to cause errors when opening shader files and replaced it with my solution. If unwanted I will revert this and can open an extra PR.

[KoBeWi]

Seems to work correctly.
The debugger changes need review from someone more familiar with the debugger.

[KoBeWi]

This is super hacky. Ideally these plugins should have exposed singletons.
Alternatively, it would be better if you at least fetched the plugins once, e.g. in NOTIFICATION_READY. And also add ERR_FAIL_NULL/DEV_ASSERT to check if they exist.

[TheDying0fLight]

I added singletons to the plugin classes.

Also I was wondering, this is used in a similar way in other locations. What is the difference or should they also be changed?

godot/editor/script/script_editor_plugin.cpp

Line 3600 in 20d58a3

ShaderEditorPlugin *shader_editor = Object::cast_to<ShaderEditorPlugin>(EditorNode::get_editor_data().get_editor_by_name("Shader"));

godot/editor/shader/visual_shader_editor_plugin.cpp

Line 8271 in 20d58a3

ShaderEditorPlugin *shader_editor = Object::cast_to<ShaderEditorPlugin>(EditorNode::get_editor_data().get_editor_by_name("Shader"));

[KoBeWi]

Editing something in the inspector does not open the relevant editor.

[TheDying0fLight]

Without this line the editor does not switch to the Shader Editor. I tried this by being on the Output dock and reloading the project with a broken shader attached to a node in a open scene. But I just found out that this basically just calls EditorNode::get_singleton()->push_item(res.ptr()) which also works. I will use that instead