Redesign VisualScriptYield

### Describe the project you are working on

VisualScript plugins and usability

### Describe the problem or limitation you are having in your project

VisualScriptYield is not working. More info in PR https://github.com/godotengine/godot/pull/48687
Now that GDscript2.0 uses `await` it seems outdated and in need of a rework anyway.

### Describe the feature / enhancement and how it helps to overcome the problem or limitation

re-evaluate.
visual_script_yield_nodes.cpp
visual_script_yield_nodes.h

### Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

I do not know the details around `await` to make this judgment.

### If this enhancement will not be used often, can it be worked around with a few lines of script?

I see no workaround.
Its best that VisualScript and GDScript are as similar as possible to remove confusion.

### Is there a reason why this should be core and not an add-on in the asset library?

`await` is core in GDscript.