_**READ BEFORE MERGING:** All PRs require approval by both Server AND
SDK teams before merging! This is why the number of required approvals
is "2" and not "1"--two reviewers from the same team is NOT sufficient.
If your PR is not approved by someone in BOTH teams, it may be summarily
reverted._

<!-- Describe what has changed in this PR -->
**What changed?**
Added new fields for links to Nexus `StartOperationResult_Sync`

<!-- Tell your future self why have you made these changes -->
**Why?**
So that links can be attached to sync operations

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

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

<!-- Describe what has changed in this PR -->
**What changed?**
Add "activity_paused" flag to RecordActivityTaskHeartbeatByIdResponse.

<!-- Tell your future self why have you made these changes -->
**Why?**
1. It is needed to let long-running activity know that activity was
paused on the server.
2. Because it is missing in RecordActivityTaskHeartbeatByIdResponse but
present in RecordActivityTaskHeartbeatResponse

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

* Update Cloud API

* use main branch

* Fix proxy manipulation of single payload fields

* Remove case for *common.Payload