Add support for cloud storage APIs

[chandrashekar-s]

The Sensing SDK repo illustrates how sensors can be used to capture data from android devices and upload the same to cloud storage systems. It also integrates with android FHIR SDK to capture user information using sensor with FHIR-SDC and create FHIR resources.

The current gap is that, the authentication and authorization for the APIs to cloud storage is handled outside of FHIR Gateway, i.e. the sensing SDK module in Android directly interacts with the cloud storage.

The main intent here is to add capabilities to the FHIR Gateway, so that it acts as a proxy to the cloud storage and handles the authentication and authorization pieces in the same way it handles for the FHIR server and FHIR Gateway becomes a single point of contact for Auth related policies.

[chandrashekar-s]

@MJ1998 @bashir2 FYI