In case standalone watcher-api runs behind forwarders (like load
balancers), it should parse specific request headers to determine
the endpoint url clients actually use.
Add http_proxy_to_wsgi middleware to api pipeline to handle this.
Closes-Bug: #2122353
Change-Id: I27ade17f7ce1649295f92f3ea1af620df63ba1bc
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>
