experiment: verify how nix pkgs.writeText works using golang's txtar & scripttest

[AmitKumarDas]

• UseCase: Build, Run & Test the discussion mentioned in the following thread
• Title: How to use pkgs.writeText
• Thread: https://discourse.nixos.org/t/how-to-use-pkg-writetext/19098/3
• Refer:
  • https://github.com/rsc/script/tree/v0.0.2

[AmitKumarDas]

Next Experiment(s)

• UseCase: Build, Test & Run the discussion mentioned without using custom txtar parser
• Refer: https://cs.opensource.google/go/x/tools/+/refs/tags/v0.22.0:cmd/gonew/main_test.go