Create automated tests

[TechnicJelle]

• [x] Create tests
  • [x] Research testing frameworks for Java (Perhaps have a peek at how BlueNBT's automated testing works...)
  • [x] Create a server with each Minecraft version, starting with 1.13
  • [x] Place signs in the world
  • [x] Copy the region file into the repository to use for the tests
  • [x] Write the actual tests, using the copied region files, so each Minecraft version should be covered
• [x] Automate them with GitHub Actions

[TechnicJelle]

Created tests in 384c8f9607babc6309bd33894c224b90d02f7484 and automated them in 2b99fb51075e4656362bbe12c541e123777e8144