Sam/add flake parts

[samrose]

What kind of change does this PR introduce?

• updated the package to make go have a default, but also allow other flakes to specify a version of go.
• • our downstream flake cannot yet switch nixpkgs until another PR is merged, so this arg allows us to pass in the 1.24 version of go downstream and succeed in building
• Introduced flake-utils to handle systems
• switched the build to use buildGoModule to allow nix to vendor the go.mod deps correctly in the build
• made a wrapping makeGateKeeper function to afford args passed in
• adding dependencies for building on macos/darwin