Enable external feeds for Platform Hub

[denys-octopus]

Prerequisites

• I have searched open and closed issues to make sure it isn't already requested
• My team has started working on this issue
• I have written a descriptive issue title

The enhancement

The Need

Platform Hub templates need a possibility to configure external feeds, which can be used by the templates.

Solution

Introduce "External Feeds" in Platform Hub. Templates now can references packages from feeds configured in Platform Hub.

Screenshots and Mockups

Links