Expand support of X-FHIR-UPDATE-IF-MODIFIED to batch/transaction entries

[lmsurpre]

Is your feature request related to a problem? Please describe.
In #2263 we added support for a server-side update optimization.
However, this optmization was only implemented for PUT requests.
Now I'd like to expand that to apply to batch/transaction interactions that contain PUTs as well.

Describe the solution you'd like
When users set X-FHIR-UPDATE-IF-MODIFIED to true, each PUT request within the bundle will be processed according to the "skippableUpdate" processing.

Describe alternatives you've considered

Acceptance Criteria
1.
GIVEN an existing resource in the server
WHEN we get an update request as part of a batch request
AND the X-FHIR-UPDATE-IF-MODIFIED header is set to true
THEN avoid performing the update
AND return the existing resource as appropriate (per the Prefer: return request)

Additional context

[kmbarton423]

Ran a variety of bundles with PUT requests (both type=batch and type=transaction) with a mix of resources that were and were not equivalent to what already persisted. Confirmed the following OperationOutcome was received for those resources where equivalency was true and X-FHIR-UPDATE-IF-MODIFIED was test to true:

            "resourceType": "OperationOutcome",
            "issue": [
                {
                    "severity": "information",
                    "code": "informational",
                    "details": {
                        "text": "Update resource matches the existing resource; skipping the update"