Add connection between OpenMRS encounter to visit

Visits were introduced in OpenMRS 1.9.  Encounters should be linked to a visit.  If a visit is already open for the encounter (based on encounter_datetime), the encounter should be connected to that visit.  If a visit is not already open, a visit should be created.

Not sure if this is customizable for place that don't use/want visits, but Partners In Health uses these for all our encounters.

Use cases:

• Patient is registered and checked into the hospital (visit started + registration encounter), vitals taken (vitals encounter), admission to COVID isolation via mUzima (encounter), discharge (discharge encounter + visit closed).
• Patient is admitted to COVID isolation via mUzima (encounter) but the visit hasn't started.  The admission encounter should start the visit.

Simon Savai Benard Mokaya - Please move to appropriate project, add epic and estimates.