Update Shader and UniformsUtils

[vanruesc]

Shader

Added the missing defines property to the Shader interface which is often needed for use cases involving Material.onBeforeCompile hooks. The property is optional because not all materials have defines:

UniformsUtils

The params and return values of UniformsUtils.clone() and UniformsUtils.merge() now use concrete types to avoid troubles with any in user code.

[Methuselah96]

Don't worry about the test-examples build failing too much, working with the examples testing is not well documented, so I can fix those.

[vanruesc]

Should I rename Shader to WebGLProgramParametersWithUniforms? I think Shader works too as a parameter type.

[Methuselah96]

I was actually thinking we'd keep Shader as-is, since it's really just intended to describe the type of shaders in ShaderLib. Maybe it should be renamed to ShaderLibShader to make that more clear? I was thinking we'd export a WebGLProgramParametersWithUniforms interface from WebGLRenderer.

[vanruesc]

I've exported WebGLProgramParametersWithUniforms from WebGLPrograms since it's used there as a param type for acquireProgram. Is there a specific reason why it should be in WebGLRenderer?

[Methuselah96]

No, that should be fine, thanks.

[Methuselah96]

Nice work, thanks for taking that on! Will review soon.

[Methuselah96]

Thanks, that was more work than anticipated!

[vanruesc]

Yeah, and those mixed types were throwing me off 😅 Thanks for the help!