Provide a mechanism for the jtrunner to inject custom jti parameters

Currently the jck jtrunner get the required jti value from https://github.com/adoptium/aqa-tests/tree/master/jck/jtrunner/config
these values are not overridable via any custom means say a custom private value is required for say "ftpURL" (eg.https://github.com/adoptium/aqa-tests/compare/master...revert-5588-jckftp_pwd?expand=1), then it is not currently possible.

Can we provide a mechanism for the jck jtrunner to take a custom local jti additional/override option set?

Start by reading the jck/jtrunner/config directory and tracing how jtrunner loads the required JTI values. Define how a local additional or override option set supplies values such as ftpURL without changing the repository defaults. Done means a custom value can be provided and takes effect during a JCK jtrunner run.

Written by the indexing model from the issue text.