Triggers API Group change in Triggers v0.4.0

[ncskier]

Issue tektoncd/triggers#332 proposes to change the API Group for Triggers resources. This will break the Webhooks-Extension.

cc @dibbles
cc @a-roberts

[ncskier]

This Triggers issue was moved back to the v0.4.0 release, because it will break the upgrade process to the next version of Triggers. I think that all Triggers resources will probably have to be deleted and then re-created.

[a-roberts]

I handled this as part of another issue and @ncskier has been working with Rodolfo on a webhook migration strategy, nothing to do here now so closing