Pathling: Explicit oauthMetadataUrl in bulk-submit allows OAuth client credential exfiltration

Pathling is a set of tools that make it easier to use FHIR and clinical terminology within health data analytics. Prior to version 2.0.0 of Pathling Server, Pathling's bulk-submit operation allows an allowed submitter to supply an explicit `oauthMetadataUrl` parameter that is not validated against `pathling.bulkSubmit.allowableSources`. When present, the bulk-submit OAuth flow trusts metadata and the returned `token_endpoint` from the caller-chosen location, then builds outbound OAuth client authentication directly from the submitter's stored credentials. This is fixed in Pathling Server 2.0.0.