add warning info to $healthcheck OperationOutcome when deployment update required

[kmbarton423]

When the database schema is more up-to-date than the code, you receive the following log messages upon executing $healthcheck:

[2/11/22, 17:57:14:821 UTC] 00000047 FHIRRestServl I Received request: tenantId:[default] dsId:[default] user:[fhiruser] method:[GET] uri:[https://localhost:9443/fhir-server/api/v4/$healthcheck] [2/11/22, 17:57:15:065 UTC] 00000047 FHIRPersisten W Deployment update required: database schema version [25] is newer than code schema version [24] [2/11/22, 17:57:15:083 UTC] 00000047 FHIRRestServl I Completed request[0.262488459 secs]: tenantId:[default] dsId:[default] user:[fhiruser] method:[GET] uri:[https://localhost:9443/fhir-server/api/v4/$healthcheck] status:[200]

The $healthcheck is still successful by design:

{
	"resourceType": "OperationOutcome",
	"issue": [
		{
			"severity": "information",
			"code": "informational",
			"details": {
				"text": "All OK"
			}
		}
	]
}

This is an enhancement request to include the warning information for the above situation in the OperationOutcome of the $healthcheck as well as the log.

QA guidance

Verify HTTP 200 is still returned, but when "Prefer" HTTP Header is set to "return=OperationOutcome", the OperationOutcome contains a warning.

{
	"resourceType": "OperationOutcome",
	"issue": [
		{
			"severity": "warning",
			"code": "informational",
			"details": {
				"text": "Deployment update required: database schema version [26] is newer than code schema version [25]"
			}
		}
	]
}

[lmsurpre]

team decision: $healthceck should continue to pass (200 OK), but it might be helpful to include it as an informational message in an OperationOutcome response

it might make sense to do this one together with #3031

[lmsurpre]

please don't make this change until we've updated our config for #3131 so that we don't fill our logs with the "client hung up" exception

[tbieste]

Since #3131 is currently in another PR, I went ahead and worked on this issue.

[tbieste]

Verified that when the schema version is higher than the code version, HTTP 200 is returned by $healthcheck with the following output:

{
	"resourceType": "OperationOutcome",
	"issue": [
		{
			"severity": "warning",
			"code": "informational",
			"details": {
				"text": "Deployment update required: database schema version [26] is newer than code schema version [25]"
			}
		}
	]
}