The convert program is only used by the shaders from package gpu, and
we're about to make the backend package imported by the program internal
to package gpu. Move the converter below package gpu.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The package app/internal/d3d11 now contains only the GPU backend on
Direct3D. Move it below package gpu to reflect that.
Signed-off-by: Elias Naur <mail@eliasnaur.com>