Single Activity API changes (#534)

<!-- Describe what has changed in this PR -->
**What changed?**
This PR  contains  a commutative feedback for single activity API:
* add 'jitter' fields to Reset and Unpause
* 'Flatten' unpause. Previous approach was marked as overcomplicated
* Add 'keep_unpause' flag to Reset. By default reset will also unpause
the activity.
* Remove no-wait flag. By default, if activity is in retry, they will be
scheduled immediately (*jitter)
* Add "activity type" as a routing parameter to every activity
operation. If activity type is provided - every pending activity of this
type will be paused/reset/updated/unpaused
* Update API descriptions to reflect those changes.

<!-- Tell your future self why have you made these changes -->
**Why?**
Working on single activity API feedback from the design review.

<!-- Are there any breaking changes on binary or code level? -->
**Breaking changes**
Yes

<!-- If this breaks the Server, please provide the Server PR to merge
right after this PR was merged. -->
**Server PR**
[Add batch activity unpause. Single activity commulative
changes](temporalio/temporal#7169)