Add workflow rules proto definitions (#558)

<!-- Describe what has changed in this PR -->
**What changed?**
Note:
->[Previous PR we use to
review](https://github.com/temporalio/api/pull/550)<-
It has lots of discussion, and current implementation is mostly what we
settle on. With some changes from design review.

Add definitions for the following API:
* CreateWorkflowRule
* DescribeWorkflowRule
* DeleteWorkflowRule
* ListWorkflowRules

Add definitions for Rules, and Actions.
Corresponding Server PR contains implementation of those APIs.

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**Why?**
Working on workflow rules.

<!-- Are there any breaking changes on binary or code level? -->
**Breaking changes**
New API is added.

<!-- If this breaks the Server, please provide the Server PR to merge
right after this PR was merged. -->
**Server PR**

[Implementation](temporalio/temporal#7437)

Author: ychebotarev