UI support for N1QL transactions

UI changes needed for supporting N1QL transactions.

1.Multi-statement transactions

BEGIN WORK

returns "txid"

This "txid" needs to be sent to all subsequent statements until COMMIT WORK/ROLLBACK WORK.

Also, all the statements from BEGIN WORK until COMMIT WORK/ROLLBACK WORK need to go to the same query node.

2.Implicit transaction

Support for "tximplicit"

This will be used for single statement transactions like an update/delete that touches 100's of documents.

Discussed in meeting with Eben and Rob - Oct 13 2020