Support for relative folder in environment definition

[yorugac]

Currently, relative folder in configuration of environment results in an error:

const env = new Environment({
  name: "basic-testrun-1",
  implementation: "vcluster",
  initFolder: ".",
})
...

// error
stat .: no such file or directory

So the path to initFolder must be absolute.

Figure out how to bypass this limitation and support relative path. Consider security concerns if any.