Support non-flakes.

[vic]

There's nothing stopping us to provide another application like our current .#write-flake which generates flake.nix.

We could

1. Generate a nix file that provides a runner using npins to import dependencies.
2. Create a json representation of inputs/follows. (like flake lock ?)

Any other ideas? This would enable dendritic modules to be less flake specific.

eg, most of my libs, like import-tree, flake-aspects (despite the name), and den (has support for custom output params but will need small changes) are designed for a non-flake world. We just need to make it happen.

[vic]

We now have unflake support. unflake itself has a backend to generate npins or unflake.nix. so npins is covered by it.

It might be interesting to see if we can support other tools in this space:

• nixtamal
• reflake
• nixlock

only if people find any of those useful enough.

[vic]

Support for npins done at #63

[vic]

Support for nixlock done at #76