Upgrade to pac4j 6.x, require Java 17 or newer, and migrate to EE 9

[basil]

Passes mvn clean verify and ATH's plugins.OicAuthPluginTest, but I am not very familiar with this plugin so I do not know if there is additional work that needs to be done. I am not planning on working on this PR any further, so please treat this PR as a starting point if and when it is desirable to complete this migration.

Testing done

• mvn clean verify
• ATH's plugins.OicAuthpluginTest

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.19%. Comparing base (84359ac) to head (b8348b0).
Report is 9 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #455      +/-   ##
============================================
+ Coverage     71.73%   72.19%   +0.45%     
- Complexity      222      224       +2     
============================================
  Files            17       17              
  Lines          1033     1050      +17     
  Branches        148      148              
============================================
+ Hits            741      758      +17     
  Misses          201      201              
  Partials         91       91              

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[fcojfernandez]

I've got a WIP branch with this same effort (except on the jdk-17 stuff), but I didn't have the bandwidth to complete it

[michael-doubez]

Duplicated by #491

[basil]

@michael-doubez Closing a PR with a passing CI build in favor of one with a failing CI build?

[pankajy-dev]

Changes looks good.
Got a review comment on duplicated PR which needs to be addressed.