feat: parametrize user claim identifiers using env vars and add user association service provider factory
This MR accomplishes the following
Introduces the ability to pass principal identifiers via environment variables. For invoking entitlements-svc APIs, this principal identifier is read from the environment variable
USER_ID_CLAIM_FOR_ENTITLEMENTS_SVCand for all others it is read from
Provides an ability to obtain user-association-service-provider using a factory. Using typescript decorators and corresponding identifiers, user-association-svc-providers can now be extended. The runtime using the environment variable
USER_ASSOCIATION_SVC_PROVIDERcan instantiate the right provider. For instance, when the environment variable
USER_ASSOCIATION_SVC_PROVIDERis set to
slb-ccm-internal, the associated implementation of the user-association-svc interaction can be used by the consumer.