Query client

[alvarowolfx]

Tracking issue for work on the new query client for BigQuery using the new package that lives in the autogen branch

• QueryClient
• Query Handler and execution flow
• Client Options for Billing Project
• Query Request helpers
• Query Parameter helpers
• Row and Value parsing for BigQuery/v2 source
• Row Iterator and page token option
• adapt package and row decoding into user defined struct
• Job retry based on error reason codes
• Storage Read API acceleration and related Client Options
• database/sql experimental driver

Draft implementation of query client: #1491