CustomHeaderAuthenticationBackend to run container proxy behind trusted http proxy

[raulbla]

I have tried to implemented what suggested openanalytics/shinyproxy#297.
Right now the authentication part is covered. So if you have a web server (eg. Apache HTTPD) which authenticates the users than the authentication header can be used to authenticate in ShinyProxy.

[LEDfan]

Hi, thanks a lot for opening this PR! We will include this in the next release!
I will merge this PR locally and push the changes to github before then next release.
Thanks again :)

[steven-sun]

@LEDfan Hi, when will this commit be merged? this will be very helpful in my current project, thanks a lot!

[LEDfan]

Hi @steven-sun , @raulbla , while working on the latest release, I tests this code but it wasn't working for me.
Could you please check whether your code still works with the latest release? I'll then further review it.

[raulbla]

Hi thanks for the hands up.
It was necessary a porting to java 17.
Can you double check please?

[danibo]

It would be great to have this feature!

[FedericoBianca]

Hi @LEDfan, do you think we'll have this new feature in the next release? I'm using it with Java17 and behind an Apache HTTP server it works as expected.