[Mesh Nodes] Ensure derivatives are allowed in mesh nodes

[pow2clk]

Is your feature request related to a problem? Please describe.
Derivatives are allowed in broadcasting and mesh shaders. They should be allowed in mesh nodes as well at least on platforms that support it.

Describe the solution you'd like
At least where derivatives in mesh shaders are allowed, derivatives should be available in mesh nodes. Testing should confirm this and possibly the mesh derivative feature flag should be set accordingly.

Describe alternatives you've considered
I'm unsure if the mesh derivatives flag should be required here as broadcasting node derivatives are already available wherever work graphs are

[pow2clk]

Seeing as I don't expect to do this myself at this point, I'm leaving this untriaged so it will be noticed and possibly assigned while I'm gone.