[Feature Request] Rollback mode

[drewhoskins-temporal]

Is your feature request related to a problem? Please describe.

For users who use ramping.
Having upgraded from v1 to v2 and set v2 to current, some users would want to instantly roll back to v1 if they discover an issue.

Can allow users to configure a rollout strategy for rollbacks?

Describe the solution you'd like

Additional context