Adds another field, named "request.method", to the structured logfile audit.
This field is present for all events associated with a REST request (not a
transport request) and the value is one of GET, POST, PUT, DELETE, OPTIONS,
HEAD, PATCH, TRACE and CONNECT.
Documents the new structured logfile format for auditing
that was introduced by #31931. Most changes herein
are for 6.x . In 7.0 the deprecated format is gone and a
follow-up PR is in order.