Triage for issues, cherry picking, and other plugins

[shaneutt]

What would you like to be added:

• Upstream-style triage implemented for issues.
• Cherry-picking enabled (e.g. /cherry-pick)
• (optional) look for other convenient plugins and integrations we might benefit from

Why this is needed:

We currently do triage in a very manual way and it's a bit tedious.

Additional Notes:

https://github.com/kubernetes/test-infra/blob/master/config/prow/plugins.yaml

[shaneutt]

kubernetes/test-infra#29270 is intended to resolve this.