Add support for login via OpenID Connect

[jwalcorn]

This Gatling-based stress client works great when Stock Trader is configured to use Liberty's basicRegistry for its login (using its hard-coded stock/trader credentials). But when the CR yaml is updated to use OpenID Connect instead, that won't work. Instead of seeing my login.jsp, you'll get redirected to the OIDC provider's login page, such as this one that I get from KeyCloak:

Upon successful login (like ultimately to RACF in the example above, as KeyCloak uses its "user federation" to call the Tivoli LDAP server on our mainframe in Brazil), it will then redirect back to Trader's summary.jsp (with the JWT issued by KeyCloak in a cookie), and all is as usual from then on.

We need to figure out how we would get this (very useful!) Gatling-based test harness working when OpenID Connect mode is enabled.

[jwalcorn]

so Karri is working on re-recording (via https://docs.gatling.io/tutorials/recorder/) the use of the Stock Trader UI, with KeyCloak OIDC-based login enabled. then we should be able to merge the part of that recording that does the login (with the 301 redirect to the KeyCloak login page) into our RecordedSimulation.scala, and we should be good. We will have to figure out if there's some parameter we can pass when launching the run to tell it whether to use the stanza for OIDC login or my login.jsp (or if we need two separate Scala files and picking between them when launching the run, or whatever).