Add support for Stream Transactions

[DiscoPYF]

We currently have support for js-transactions only, in TransactionApiClient. The transactions API of ArangoDB also supports streaming transactions, which are a different kind of transactions from js-transactions.

HTTP Interface for Transactions
https://www.arangodb.com/docs/stable/http/transaction.html

HTTP Interface for Stream Transactions
https://www.arangodb.com/docs/stable/http/transaction-stream-transaction.html

[DiscoPYF]

The way I see it, we should be able to update ITransactionApiClient and the TransactionApiClient implementation with methods that mirror the HTTP endpoints for begin/check/commit/abort/list operations. Keeping js and streaming transactions methods together in the same transaction client will be easier for consumers.

[DiscoPYF]

As discussed separately with @DiscJockeyDJ , this work is split in a series of pull requests. The first one added the methods for the stream transaction API endpoints. A subsequent pull request will be opened to allow speciying the transaction ID in other API operations.