Support specify dispatch policy for the non-key message in Key_Shared subscription mode

Master issue: #4077
**Is your feature request related to a problem? Please describe.**
Currently, the non-key message dispatch to a consumer in Key_Shared subscription mode. It's better to support set up the dispatch policy at the client-side.

**Describe the solution you'd like**
Allow the client to set up a ` non-key` message dispatch policy.

Start with master issue #4077 and the Key_Shared subscription behavior described here; no source file or test is named in the issue. Clarify the supported non-key message dispatch policies and the client-side configuration surface, then define completion through tests covering the selected policy.

Written by the indexing model from the issue text.