[FEAT] Blended PBR textures to support normal and rma maps, and fix broken blending when lightmaps broken

[valina354]

Is your feature request related to a problem? Please describe.
i want to use blended textures to create cool scenes, but they only support albedo, and on top of that they are broken when lightmaps are broken

Describe the solution you'd like
by making pbr_blend support normal_map2 and rma_map2 and params and them working in shader, along with fixing the lightmap bug

Describe alternatives you've considered
theres not really any alternative

Additional context
Image of bug that happens when theres lightmaps (slightly outdated from main not sure if still happens but most likely yes):

[Silverlan]

Lightmap support for meshes with blend-alphas has now been added (dcd183e), which should fix the texture issues after baking.