Provide a web UI for configuring manifests

[saheljalal]

It would really cool to add a nostromo web command that could spin up a web server that can manage the manifest(s) from the UI. The web app can access the config file and update it as the user makes modifications.

The web UI should be snazzy and intuitive that can show users their config visually. In the future, when we support multiple manifests, like synchronizing from a repo or copying from somewhere, the UI could expose everything.

Initially, show which manifest is being used (main or supplementary) and show all the commands available as nodes. Let users drill down into each command and sub-command to see and modify details like the description, the command, and other attributes. Allow key functionality from the command line like adding and removing commands and substitutions, search.

Later, drag and drop would be interesting if we could move commands around (nice to have).