Make ocm flake.nix ready

[vasu1124]

Description

This is a flake enablement for the repository of ocm. nix enabled environments can easily import ocm with

nix run github:open-component-model/ocm
nix run github:open-component-model/ocm#demo
nix run github:open-component-model/ocm#helminstaller
...

nix can hermetically build the package automatically on various architectures. With the flakes includes the the ocm repo, we can contribute our project into the nixos.org package library.

What type of PR is this? (check all applicable)

• [x] 🍕 Feature

Added tests?

• [ ] 👍 yes
• [x] 🙅 no, because they aren't needed
• [ ] 🙋 no, because I need help
• [ ] Separate ticket for tests # (issue/pr)