Update feed selection from predefined list #369
Description
A nice optional feature would be to be able to select update feed from a predefined list. Currerntly the feed input accepts freely typed text.
E.g. Admin defines a list of available feeds (early access, beta, stable, lts,...) and then Ops people can only choose from one of this predefined feeds when setting up new devices (and rollouts).
We could define the list of available feeds directly in config or optionally make it configurable through UI.
A drop-down list of available feeds would be displayed when selecting the feed in Device tab and in Rollouts tab when creating new release.