Issue #, if available:

Description of changes:

1. Emit "requestReadLatencyMS" in the response summary and add a corresponding metric to indicate how long from when the request head was received until the request was complete and the operation could be handled.
2. Decorate the operation logger with the Operation using the incomingOperation metadata key.
3. Combine multiple request headers into a single log metadata entry
4. Ignore headers with value "none"

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.