flake-parts: add nix run interface along with devenv container subcommand and improvements

[nazarewk]

The state of implementation of flake-parts from #360 wasn't really usable in practice:

1. no way to make an image to upload to registry due to nix2container's patched skopeo not being exposed,
2. no way to run the image because nix2container doesn't package an usable image with current invocations,

This PR makes following additions:

1. make clear the package is not a runnable container by appending it with -spec,
2. adds devenv container [options] [container-name] family of commands for flakes
   1. adds --podman-run
   2. adds local registry aliases
   3. allows passing arguments to docker/podman and container run command itself
3. adds .envrc
4. adds default certificates to the container
5. allows passing arbitrary configuration to container build

TODO:

• update docs
• write tests

[nazarewk]

I've successfully built and used the devenv container setup using this branch, so it's ready for review.

[domenkozar]

Not to maintain the cacertificate list here, can we just use dockerTools.caCertificates?

[domenkozar]

Seems like CI is pointing to a regression?

[nazarewk]

fixed the failing test (I renamed the output, but didn't touch the tests)

[nazarewk]

looks like docopts doesn't build for Mac?

[nazarewk]

@domenkozar how do you handle docopts on Mac?

from https://github.com/cachix/devenv/actions/runs/5197759077/jobs/9399642874?pr=503#step:6:921

error: Package ‘docopts-0.6.4-with-no-mangle-double-dash’ in /nix/store/lm6klhgwfz7inymhgf8siwpypjrvdla7-source/pkgs/development/tools/misc/docopts/default.nix:26 is not supported on ‘x86_64-darwin’, refusing to evaluate.

[zane]

Suggested change

	echo "devenv could not be build. The devenv environment was not loaded. Make the necessary changes to devenv.nix and hit enter to try again." >&2
	echo "devenv could not be built. The devenv environment was not loaded. Make the necessary changes to devenv.nix and hit enter to try again." >&2

[domenkozar]

would be really great if someone can rebase this on top of #745

[domenkozar]

I've ported a few things from this PR to #1005, but it would be great to get the rest of the changes in.

[nazarewk]

Hello, sorry for lack of updates, but I am currently trying to spread Nix at workplace by using https://github.com/divnix/std + Hive (best intro at https://primamateria.github.io/blog/hive/) and those integrate with https://github.com/numtide/devshell instead. Between this work situation and very different ongoing personal project I doubt I will have time to get back into devenv in foreseeable future.

[domenkozar]

Hey, fair enough I'll close this then :)