Add flag to restore activity options to reset and update (#593)

<!-- Describe what has changed in this PR -->
**What changed?**
Add flags to activity reset/activity update-options requests to support
"restore original options" behaviour.

<!-- Tell your future self why have you made these changes -->
**Why?**
They will help users to "reset" their changes.

<!-- Are there any breaking changes on binary or code level? -->
**Breaking changes**
No

Author: ychebotarev