[#32] Add CLI options parsing

[YuriRomanowski]

Description

Problem: Currently, our program has no CLI infrastructure with program description, helps etc. Also, there is no way to dump the default config with useful explanations.

Solution: Add optparse-applicative CLI parser that supports the default mode (run the Slack timezone bot) and also additional dump-config command.

Related issue(s)

Fixed #32

:white_check_mark: Checklist for your Pull Request

Related changes (conditional)

• Tests

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

• Documentation

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

Stylistic guide (mandatory)

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

[Martoon-00]

Hm, interesting indentation in the commit message.

If you are planning to use it further, I'd recommend writing in Slack (probably into #engeneering channel) and ask how much is it worthy to do so. I think eventually we must use a uniform approach, and I actually see some pros in going with the indentation.

[YuriRomanowski]

Hm, interesting indentation in the commit message.

If you are planning to use it further, I'd recommend writing in Slack (probably into #engeneering channel) and ask how much is it worthy to do so. I think eventually we must use a uniform approach, and I actually see some pros in going with the indentation.

Hm, that was just a strange fluctuation :smile: I'll reword this commit