Implement payload offload support for Azure Blob

[punktilious]

Is your feature request related to a problem? Please describe.
Relational database systems are not best suited to storing large objects. This can lead to increase runtime costs as well as scalability limitations.

Describe the solution you'd like
Following the groundwork done in #1869 and #2900, implement payload persistence offloading for Azure Blob.

The solution must provide a mechanism for cleaning orphaned records which may remain after a failed transaction.

The solution should consider using asynchronous patterns for storing and fetching the payload data. This will be important when processing large bundles to maintain acceptable response times.

Describe alternatives you've considered
Accept the limitations and cost of keeping the payload within the RDBMS.

Acceptance Criteria

GIVEN a server configured with payload persistence for Azure Blob enabled
AND a new resource is ingested
WHEN the transaction is successful
THEN the resource can be read back
AND the payload can be found in the offload storage

GIVEN a server configured with payload persistence for Azure Blob enabled
AND a new resource is ingested
WHEN the transaction is rolled back
THEN the payload can not found in the offload storage

GIVEN a server configured with payload persistence for Azure Blob enabled
AND a new resource is ingested
WHEN the transaction fails and rollback is not possible (e.g. network partition)
THEN the payload is removed from the offload storage after the cleanup reconciliation process is run

Additional context
Design discussion to be had regarding how, where and when to run the transaction cleanup process.

The payload persistence mechanism is not tied to a Liberty Datasource so Liberty's transaction recovery mechanism doesn't apply. The discussion is really about whether the cleanup process should be a separate standalone job, or a background thread started by the FHIRServletContext.

Work for this feature should consider #2900 which implements the same offloading mechanism using Cassandra.

[d0roppe]

Was running some concurrent create/delete and this seems to have caused a issue with Azure.Blob offload active.

[d0roppe]

Tested many scenarios with Azure.blob offload, and currently I have not found any new problems. Closing issue