Follow-up to #322

The library now supports Stream Transactions and using them with the Document and Cursor APIs. The Collection and Graph APIs need to be updated to allow passing a transaction ID.

https://www.arangodb.com/docs/stable/http/transaction-stream-transaction.html

Supported transactional API operations include:
All operations in the Document API
Number of documents via the Collection API
Truncate a collection via the Collection API
Create an AQL cursor via the Cursor API
Handle vertices and edges of managed graphs (General Graph / Gharial API, since v3.5.1)