[#23] Add `bats` tests

[DK318]

Problem: In #29, we implemented almost every CLI action, but we haven't written any tests for them yet.

Solution: write golden tests using bats.

Description

Related issue(s)

• Resolves #23

  Related changes (conditional)

  • Tests

    • [x] If I added new functionality, I added tests covering it.
    • [x] If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

  • Documentation

    • [x] I checked whether I should update the docs and did so if necessary:
    • README
    • Haddock

  • Public contracts

    • [x] Any modifications of public contracts comply with the Evolution of Public Contracts policy.
    • [x] I added an entry to the changelog if my changes are visible to the users and
    • [x] provided a migration guide for breaking changes if possible

  Stylistic guide (mandatory)

  • [x] My commits comply with the policy used in Serokell.
  • [x] My code complies with the style guide.

[dcastro]

Can you please also make a small amendment to the make bats target? To make it easier for us to run a specific test (or subset of tests)

# Usage:
#   * make bats
#   * make bats FILTER="test name"
bats:
    git submodule update --init --recursive
    ./tests/golden/helpers/bats/bin/bats ./tests/golden/** $(if $(FILTER),-f "$(FILTER)",)