When using a haproxy with SSL termination to provide secure console
connections, haproxy will change the Origin header scheme to 'http'
and add the 'X-Forwarded-Proto: https' header. This causes a failure
in the Nova console proxy code which verifies that the Origin header
scheme matches the access_url scheme for the connection, because the
Origin header coming from haproxy is 'http' while the access_url
scheme is 'https' or 'wss'.
This looks for the X-Forwarded-Proto header and uses its scheme for
the verification instead, if it is present.
Closes-Bug: #1788180
Change-Id: I43401dc8368853654bf443273a0a1b5b9b63e3f0
890e2d320e