fix: canvas raw shader access

[CosmaVergari]

Problem: Raw canvas shaders still go through the convertToShader function when being set on each node. However raw shaders already contain all the info for the shader to be rendered in the shader prop.
This is due to an error in the logic flow for Canvas (in WebGL it is correctly managed).

Solution: Apply the same logic that is used in WebGL, that is: when dealing with a raw canvas shader (props.shader.render is defined) do not call convertToShader.

[chiefcll]

Can we just look for render? Do we need both program and render?

[CosmaVergari]

I think that "render" is added in the Canvas shader node and "program" in the WebGL shader node, so we should check for the presence of any of the two