Allow multiple devfile registries to be added to che

[tobespc]

Is your enhancement related to a problem? Please describe.

At the moment, the dashboard references a single location from where it gets it devfiles from. In our case, we would like to add additional devfile registries so that we can can deploy che with the blessed set and also our additional set.

Describe the solution you'd like

In che.properties, the current implementation sets

che.workspace.devfile_registry_url=https://che-devfile-registry.openshift.io/

This could be enhanced to take multiple urls which would then be processed in devfile-registry.factory.js when fetching the devfile

Describe alternatives you've considered

Another option could be having the existing https://che-devfile-registry.openshift.io/ pull in other repositories but this would be clumsy imo and hard to maintain

[tobespc]

This is something my team is working on and, providing you agree with the enhancement, will put a PR asap with a solution

[nickboldt]

FYI @slemeur @l0rd this is the contribution from IBM we talked about a couple weeks ago. PR coming soon! Setting fixversion of 7.1 for now but if you feel this is urgent for 7.0, feel free to change.

cc: @rhopp @tsmaeder re: triage.

[slemeur]

@skabashnyuk : Please check the PR as soon as 7.0 is released

[skabashnyuk]

@slemeur pr looks ok for me. However, since changes are only on the dashboard side it's better that is someone familiar with it can approve it.

[slemeur]

@evidolob + @benoitf : Could you please review?

[nickboldt]

seems the above pr was replaced by #14059 which has some failing flaky ci tests and can't be merged due to conflict w/ master branch.

2 months later... :(