As part of the Netcracker/qubership-apihub-api-processor#30 story, we are changing the way how diffs are calculated for operations. We calculate diffs in bulk, essentially comparing whole documents.
This signinficantly reduces changelog calculation time for GraphQL operations on a big specifications and to a lesser extent has the same effect for the OAS specifications.
We need some changes on backend to be able to implement the logic.

1. We need to add mapping of operation to documentId
2. We need to get rid of operation data hash, since it is no longer used by compare logic and is very expensive to calculate.

Proposed changes to the API are captured in this PR: https://github.com/Netcracker/qubership-apihub-backend/pull/192/files