feat: add a mechanism to hide top-level nav items

[gashcrumb]

relates to ENTESB-11500

This can be used to hide the "Extensions" nav item as needed, or any other item in the nav bar. Note that this currently only works for the main navigation but this can be further built upon as needed to hide other elements as needed.

It's driven by the features attribute in the config.json file and I've added some examples:

The key name corresponds to the module name, i.e. "extensions" here is compared to the URL that the navigation item has for it's route. So to hide the link to a section of the app you look at the URL bar, for example "extensions":

That's the key you'd use in the features map. And it won't blow up if these keys aren't present.

Oh, and also the "logging" entry that's being removed from the example config.json files is cruft.

[syndesisio-bot]

@gashcrumb The bot could not transition the ticket automatically, please update this Jira ticket manually: https://issues.redhat.com/browse/ENTESB-11500