FhirEngine Sync Download API Re-design

[omarismail94]

Is your feature request related to a problem? Please describe.
Modify the Android FhirEngine Download APIs to give developers more control over which FHIR resources to sync, and how to store these resources on the phone

Describe the solution you'd like
An implementation that gives developers control on exactly which FHIR resources can be synced to the phone. Developers can write the app to fetch resources via search parameters, or IDs. Developers can constrain the resources downloaded to a subset of FHIR resources. The user-supplied functions give app developers power to tailor their code to specify which resources to fetch.

Describe alternatives you've considered
Current implementation

Additional context
See: https://docs.google.com/document/d/1UZ7Ndb8JRmB2UdXpfIkPT-VAra6X2aLSzdGI_a8KJkg

Would you like to work on the issue?
Yes