💥 Remove FetchInfo and FetchResult handler requests

[mjameswh]

Description

Remove the following:

• FetchInfo and FetchResult requests from AbstractHandler and Handler classes
• fetch_info and fetch_result methods from OperationHandler abstract class
• fetch_info and fetch_result methods from both SyncOperationHandler classes
• FetchOperationInfoContext and FetchOperationResultContext classes
• OperationInfo class and its associated OperationState enum

Fix #23

[cretz]

Mentioned in .NET but will also mention here. This is technically an incompatible change to remove a type that SDKs are using. Can you put 💥 on the issue title? Also, we need to make sure not to merge this until we have a plan to release SDK and Nexus at the same time, otherwise latest SDK won't compile with latest Nexus if this is released first.