Automatically detect and enable color if terminal supports it

[mkcp]

Describe the behavior you'd like

Currently, users must specify if they want to disable terminal color (--no-color), or use a --log-format without one (e.g. json). Using https://github.com/jwalton/go-supportscolor or something similar (s/o to @phillebaba) we can check the current terminal's behavior and enable/disable color accordingly. Any user-supplied input from flags or env vars would take precedence in this case (using the usual config precedence).

Related #3306