refactor serder tests

  • Create dir with docker kind/version/call i.e. src/test/resources/samples/docker-engine/1.21/execCmd/{sample1.json, sample2.json}
  • implement tests that picking such files for tests.
  • remove enums

Goal: have json samples from different docker version and our classes should produce expected results for them.

@marcuslinke are you ok with this?