Generic bundle transformers

[rachitnigam]

It is currently impossible to write the following user-level program:

comp Flatten[W, N, M]<'G:??, 'L:??>(
  in[N][M]: for<i, j> ['G, 'L] W
) -> (
  out[N * M]: for<i> ['G, 'L] W
) where 'L > 'G {
  out{0..M*N} = in{0..N}{0..M}
}

There are a bunch of problems but the big one is that we do not allow 'L > 'G on the user-level component. A possible solution is allowing this when neither event requires @interface since it means we don't need to generate circuitry for them (which is not supported).

There are other problems where, if the bundles have dependent availabilities, we cannot pass them as inputs and its unclear if we can even pass ones with independent availabilities.