fix: reworked container architecture (#619)

- Don't set architecture, let Docker host decide it's own platform,
  remove `runtime` dependency and don't show default in `--help`
- Remove most tests, we need to check only once if it works on
  different platform
- Rename `DeleteImage` to `RemoveImage` to conform to existing
  function in `docker` cli, added options to specify `force` and
  `pruneChildren`

pkg/container/docker_run.go

@@ -293,7 +293,7 @@ func (cr *containerReference) create() common.Executor {
 		}
 
 		var platSpecs *specs.Platform
-		if supportsContainerImagePlatform(cr.cli) {
+		if supportsContainerImagePlatform(cr.cli) && cr.input.Platform != "" {
 			desiredPlatform := strings.SplitN(cr.input.Platform, `/`, 2)
 
 			if len(desiredPlatform) != 2 {