Fix T100377: EEVEE: Regression 3.2 normalmap node broken

This was caused by un-wanted normalization. This is a requirement of
the MikkTspace. The issue is that g_data.N is expected to be normalized
by many other functions and overriden by bump displacement.

Adding a new global variable containing the interpolated normal fixes the
issue AND make it match cycles behavior better (mix between bump and
interpolated normal).

source/blender/gpu/shaders/gpu_shader_codegen_lib.glsl

@@ -187,8 +187,10 @@ struct ClosureTransparency {
 struct GlobalData {
   /** World position. */
   vec3 P;
-  /** Surface Normal. */
+  /** Surface Normal. Normalized, overriden by bump displacement. */
   vec3 N;
+  /** Raw interpolated normal (non-normalized) data. */
+  vec3 Ni;
   /** Geometric Normal. */
   vec3 Ng;
   /** Curve Tangent Space. */