Improved performance for the Raw container

[s0l0ist]

Description

Feat:

• The complexity of the underlying Raw intersection computation has improved
  from O(nmlog(m)) -> O(nlog(n) + max(n, m)); however, internal protobuf
  deserialization remains as the dominant performance inhibitor for the
  client->GetIntersection* methods.

Fix:

• The go integration tests were not using the datastructure param properly.
  The fix did not result in any regression.

Chore:

• Update C++ benchmarks to include the new Raw enum variant
• Misc fixes to tests which were not rounding correctly and causing CI to fail
  randomly
• Update the main README to include a description of the protocol

Affected Dependencies

N/A

How has this been tested?

• CI

Checklist

• I have followed the Contribution Guidelines and Code of Conduct
• I have commented my code following the OpenMined Styleguide
• I have labeled this PR with the relevant Type labels
• My changes are covered by tests