[Feature Request] Allow the mesh launch type for node shaders

[pow2clk]

Essentially a renamed broadcast node. set up a skeleton. including metadata and RDAT that captures launch type and additional properties. Allows defining and refining interfaces early. Tested with blank entry points without much content.

Is your feature request related to a problem? Please describe.
In order to support mesh nodes, the compiler must accept the HLSL code that specified mesh nodes. See parent #6404

Describe the solution you'd like
Add the ability to specify a mesh node as little more than a renamed broadcasting node. This will produce the metadata and RDAT with the launch type and a few additional properties. Test with blank entry points without much additional content or complications.

[pow2clk]

Fixed by #6436