Add missing `Raw_*` complex and quaternion types

[Feoramund]

I'm not sure why those types were defined in core:mem, but I moved them to base:runtime where the other Raw_* types live.

To be clear, this adds the following types to base:runtime:

Raw_Complex32     :: struct {real, imag: f16}
Raw_Quaternion64  :: struct {imag, jmag, kmag: f16, real: f16}
Raw_Quaternion64_Vector_Scalar  :: struct {vector: [3]f16, scalar: f16}