Add support for archives in stack dependencies

[purefn]

It would be great if we could use GitHub archives in stack.yaml instead of git references. Currently, adding something like

extra-deps:
- url: https://github.com/zoominsoftware/HaskellNet-SSL/archive/5b4f4ab49a6321b57f6dbeba64a7f4bb8ffa5cbc.tar.gz

Results in the error

  stack-repos: AesonException "Error in $.packages[66]: key \"git\" not found"
  CallStack (from HasCallStack):
    error, called at lib/Stack2nix/External/Resolve.hs:45:25 in nix-tools-0.1.0.0-GyKmmsWJG7eHjjYvOTmgBD:Stack2nix.External.Resolve

Having support for this would help alleviate some of the issues with using git repos with stack, like not being able to add the reference and getting a fatal: not a tree object <revision> error. It would also be much faster, as the history of the git repo wouldn't need to be fetched.