Allow direct array indexing of array member field in a #raw_union struct

[rowbyte]

Right now, one cannot override the swizzle fields/set custom swizzle field order or names in an array type (which is understandable). A decent workaround seems to be creating a #raw_union with the struct and an array field. But direct array indexing of this struct isn't supported.

AHLS :: struct #raw_union {
      using _  : struct {
                 alpha, hue, lightness,saturation : f32
      }

      using _ : [4] f32;
 
}

Describe the solution you'd like
Allow direct array indexing of raw-unions, if there is only one array field member inside the raw union struct.

Additional context
None.