Update normalmap node to 1.39

[pablode]

Draft PR until an issue on macOS/MSL is resolved.

• I have added the null-check from GLSL and MSL to the OSL and MDL backends for consistency. As an alternative, it could be removed from all implementations.

• Tangent vector renormalization in OSL seems like a concern that should be handled by the implementation providing the geometry streams. I removed it.

• I did not check if the OSL and MDL implementations compile and pass the tests

• There is a problem on macOS/MSL. It seems that the Bworld/bitangent geomprop is not correctly provided, leading to a black material. This is not the case for the GLSL backend.