Add Raw field to atlas response

[svagner]

Description

Add Raw field in response to be able to store raw data from atlas server response

Type of change:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Required Checklist:

• I have signed the MongoDB CLA
• I have added tests that prove my fix is effective or that my feature works
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code

[gssbzn]

Small change to unblock mongodb/go-client-mongodb-ops-manager#72

We may do a follow up later with the changes we're adding to ops manager to get a raw response