Enable HTTPS support for generated URL

[dstenger]

Originally reported by @robinhoutmeyers in #68 (comment):

I also encountered a similar issue during a beta test for #66. Steps to reproduce:

• Start a WMS Client beta test session
• Open https://dev.luciad.com/portal/packed-samples/ria/dataformats/index.html?webgl&reference=epsg:4978
• Click on "Connect to..." and select "WMS"
• Fill in the proper GetCapabilities URL; e.g. (replace the number 33 with the actual number): https://cite.ogc.org/te2/monitor/33?REQUEST=GetCapabilities&SERVICE=WMS
• Click Next, select the Basic polygons layer and click Next again.

=> although the test session console and the test results (after stopping the test) will recognize the fact that a GetCapabilities and GetMap requests were received, the display during the test is never updated.

[bpross-52n]

Imho, this issue is related to mixed content served by Teamengine, i.e. mixed http/https content. We will update the Teamengine instances to provide only https content.

[bpross-52n]

@dstenger It turns out that this can be solved via configuration of the proxy and Tomcat. A RemoteIpValve needs to be set in the server.xml so that the x-forwarded-proto hearder will be recognised by Tomcat, see here:
https://stackoverflow.com/questions/5741210/handling-x-forwarded-proto-header-in-java-web-application

I added the following line to the ets-wms-client13 docker file:

RUN sed -i 's|\
  </Host>|\
    <Valve className="org.apache.catalina.valves.RemoteIpValve" \
      remoteIpHeader="X-Forwarded-For" \
      protocolHeader="X-Forwarded-Proto"/>\
  </Host>|' \
  /usr/local/tomcat/conf/server.xml

This header needs to be set in the proxy to the respective protocol. I used this for nginx: proxy_set_header X-Forwarded-Proto $scheme;. If https is requested now it is used for the tests without any necessary modification of the code.

[dstenger]

@robinhoutmeyers We updated the Beta environment. Can you please check if the problem still occurs?