Support an "env" and "sockets" feature

Now that StarlingMonkey is seeking to use runtime environment variables and sockets we might add these to the enable/disable features.

Alternatively, we might want a `debugger: true/false` ComponentizeJS option when we switch to the StarlingMonkey with debugger support.

No files, tests, or entry points are named. First clarify whether the intended work is env and sockets feature toggles, a debugger option, or both, then locate the existing enable/disable feature configuration and its tests; done should be defined as the selected options being accepted and verified by tests.

Written by the indexing model from the issue text.