Social: Improve polling for share status (#39194)

* Create pollForPostShareStatus action

* Clean up ShareStatus

* Wire up polling for post publish share status

* Fix selector type

* Add changelog

* Fix TS error

* Don't start polling if already in progress

* Fix post publish share status going back and forth into loading state

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/10700370376

Upstream-Ref: Automattic/jetpack@aa816c8