- Use canonical content address JSON format for floating content
addressed derivation outputs
This keeps it more consistent.
- Reorganize inputs into nested structure (`inputs.srcs` and
`inputs.drvs`)
This will allow for an easier to use, but less compact, alternative
where `srcs` is just a list of derived paths.
It also allows for other experiments for derivations with a different
input structure, as I suspect will be needed for secure build traces.
See #13570 for details --- the idea is that included the store dir in
store paths makes systematic JSON parting with e.g. Serde, Aeson,
nlohmann, or similiar harder.
After talking to Eelco, we are changing the `Derivation` format right
away because not only is `nix derivation` technically experimental, we think it is
also less widely used in practice than, say, `nix path-info`.
Progress on #13570
