Add CONTINUE_AS_NEW_SUGGESTED_REASON and CONTINUE_AS_NEW_VERSIONING_BEHAVIOR enums. (#677)

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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 -->
- Allow user to specify in ContinueAsNewOptions what the initial
versioning behavior of the continued-as-new workflow should be. User can
say AutoUpgrade if they want their workflow to upgrade on
continue-as-new.
- Define `CONTINUE_AS_NEW_SUGGESTED_REASON`. `suggest_continue_as_new =
true, reason = TARGET_WORKER_DEPLOYMENT_VERSION_CHANGED` will be sent to
the SDK with each workflow task, if the target version of the workflow
is different than the deployment version that the workflow is currently
on. Workflow code should listen to this and decide whether to
ContinueAsNew based on the suggestion and reason(s) for the suggestion.

<!-- Tell your future self why have you made these changes -->
We want to offer a way for users to guarantee workflow pinning within a
run, while still upgrading to the latest Current/Ramping version on the
continue-as-new boundary.

In Phase 2 of Trampolining (which is "proactive wakeup for sleeping
workflows"), a separate workflow attribute will be added to allow
workflows to receive a proactive wake-up when a new version is
available. Pro-active wakeup would cause sleeping workflows to wake up
and have the opportunity to check `continue_as_new_suggested` and
continue-as-new if they choose. This is orthogonal to "will I upgrade
when I continue-as-new," and applicable to both Pinned and AutoUpgrade
workflows.

<!-- 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**
temporalio/temporal#8784

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Co-authored-by: Spencer Judge <[email protected]>

Author: carlydf