Draft: [Chore] Switch trailing newlines check to Danger

Description

Check trailing whitespaces with danger.

Controversial points:

• I've added suggestions for fixing some newlines issues, but they appear as separate messages and that sounds annoying. On pushing new commits, those suggestions are not edited, but new suggestions are created.

  Probably better go without suggestions at all?

Related issue(s)

TM-577

✅ Checklist for your Merge Request

Related changes (conditional)

• Tests (see short guidelines)

  • 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:
    • Root README and other README.md files
    • Haddock
    • docs/
  • I updated changelog files of all affected packages released to Hackage if my changes are externally visible.

Stylistic guide (mandatory)

• My commits comply with the following policy.
• My code complies with the style guide.