Add query/insert level settings override

[slvrtrn]

This PR adds:

• Query::with_option(...)
• Insert::with_option(...)
• Inserter::with_option(...)

These methods behave similarly to the Client::with_option but allow overriding settings for a particular query/statement only.

For Insert, some internal refactoring was required to postpone creating the outgoing request.

Additionally, fixed some stale links in the code comments.