GraphNode doesn't respect mouse filter.

### Tested versions

- Reproducible in v4.2.1 Stable
- Windows 10

### System information

Vulkan API 1.3.260 - Forward+ - Using Vulkan Device #0: NVIDIA - NVIDIA GeForce GTX 1660 Ti

### Issue description

GraphNodes do not respect their mouse filter. Setting it to Ignore, Pass, or Stop does nothing.

In previous versions, GraphNodes could be set to be a Comment, and that would cause it to ignore mouse input. But in later versions this feature was removed.

I am attempting to make a node that I can 'lock', and have it ignore inputs and allow click-drag select to start on top of it. But when 'selectable' and 'draggable' are set to false, it still takes priority over mouse input over the GraphEdit. When the user attempts to click-drag select, the mouse instead turns into the dragging icon and does nothing.

Here is a video of my larger project where I discovered the issue. The first part is the intended behavior in version 4.1.1, while the second part is in v4.2.1 stable.

https://youtu.be/sqXpXIS24iU

### Steps to reproduce

- Create a new graph edit
- Create a GraphNode
- Set that GraphNode's mouse filter to Ignore or Stop
- Notice that it doesn't affect it's behavior.
- Setting Selectable and Draggable to false, still takes mouse input priority

### Minimal reproduction project (MRP)

[Graph Node Not Respecting Mouse Filter Completely.zip](https://github.com/godotengine/godot/files/14955404/Graph.Node.Not.Respecting.Mouse.Filter.Completely.zip)