SSDM-10939 : add SWITCH aai login to NG UI - allow to use ${current-url}...

SSDM-10939 : add SWITCH aai login to NG UI - allow to use ${current-url} variable in the switch-aai.link property; the variable will be replaced with the current url at the moment of rendering the link in the UI; this variable will be useful for setting the redirect-url parameter for the SSO servlet to take us back to either ELN or NG UI login page (depending on where we came from)