Add "Flakeless Parts" template

[theutz]

First, I don't love the name. 😄 npins-flake-parts? flake-parts-npins? nparts? I couldn't come up with anything. Feel free to change it.

More importantly, I was able to get npins and flake-file to play nicely, but I had to create a new module to do it cleanly. So, while this is mostly a change to the templates, there is an addition to the API.

Let me know what you think!

[vic]

CI is failing

nix run .#write-flake -L --show-trace --override-input flake-file "github:$GITHUB_REPOSITORY/$GITHUB_SHA"
warning: input '' has an override for a non-existent input 'flake-file'
warning: the flag '--override-input flake-file github:vic/flake-file/2514b92896580e5e24d2feaaf5f27fea3fd8196c' does not match any input

looks like it cannot override the flake-file input to make it the commit version

[theutz]

Oh, wait. It's not failing that test. It's getting pulled into the matrix test, which it would fail. And probably shouldn't be used. Is there a way to filter it out?

nvm, I think I found it.

[theutz]

AND, I forgot about YAML sequences. Can you push the button again, @vic ?

[theutz]

After actually reading the GitHub Actions docs for the matrix strategy, I think I figured out what I was doing wrong and why the minimal test was running. Hoping this one fixes it.

[vic]

Please merge yourself when ready.

[theutz]

Ok! Finally saw the actually relevant test turn green. I'm going for it!