Nix flake enablement for landscapercli

[vasu1124]

What this PR does / why we need it:

We want to enable landscapercli for the nix community.

# with Nix (macOS, Linux, and Windows)
nix run github:gardener/landscapercli -- version

# development version
nix profile install github:gardener/landscapercli

landscaper-cli --help

[gardener-robot-ci-3]

Thank you @vasu1124 for your contribution. Before I can start building your PR, a member of the organization must set the required label(s) {'reviewed/ok-to-test'}. Once started, you can check the build status in the PR checks section below.

needs rebasing

[In-Ko]

Thanks @vasu1124 for your contribution. Before we merge this (and therefore have to support this in the future), I'd like to know ifsomeone concretely asked for this ? Or do you have other reasons for this PR ?

[vasu1124]

Thanks @vasu1124 for your contribution. Before we merge this (and therefore have to support this in the future), I'd like to know ifsomeone concretely asked for this ? Or do you have other reasons for this PR ?

We indeed have teams that enable their dev environments with nix, which transports a number of advantages. I think the overhead is not too much. This nix flake btw. also automates the binary for aarch64. The other option that you could also consider is homebrew. => make it simple for users to consume and stay uptodate with landscaper-cli.

[gardener-robot]

@enrico-kaack-comp, @achimweigel, @robertgraeff, @In-Ko You have pull request review open invite, please check