support for UploadRequestGeneratorMode.UrlRequest in UploadStrategy (?) to support OpenMRS as FHIR Backend

[icrc-fdeniger]

@aditya-07 created a branch to demo OpenMRS integration:
master...openmrs

From what I understand the main part is here: engine/src/main/java/com/google/android/fhir/sync/FhirSyncWorker.kt
But In the last version in the main it seems complicate to apply this change easily. It seems we should activate a new UploadStrategy using UrlRequest ( not totally sure).
We can work on this but probably just need some hints to start :)

Thanks

cc @jingtang10

[icrc-fdeniger]

Thanks @aditya-07 for your inputs. Our Team could work on that point if possible.
We would need some help if possible:

• I believe that supporting UploadRequestGeneratorMode.UrlRequest is the step to make android-fhir compatible with current OpenMRS FHIR module. Is it correct ?
• Is there any point to implement ? we are using keycloak to connect to openmrs and we are able to download patients so I don't think there is other blocking point