experiment: edit go.mod using rsc's script

[AmitKumarDas]

• Refer: https://github.com/rsc/script/tree/main
• Goal: Update the declared modules to their local relative paths
• Goal: Update the declared local module paths to their latest or main commits
• Goal: Verify presence of any local module paths & error if present
• Task: hack/gomod_local_set.txt will have business logic / specifications
• Task: hack/gomod_local_unset.txt will have business logic / specifications
• Task: hack/gomod_local_err.txt will have business logic / specifications
• Future: Add this to Github actions
• Future: Implement this in pure go & provide observations on which one suits when
  • E.g.: which one is applicable to be executed as GitHub actions
  • E.g: How does environments vary in terms of build & runtime dependencies