Add developer docs

[jtnord]

Adds some developer docs, with howto use the OpenID Connect conformance tests, as well as howto setup an ADFS instance for testing.

Testing done

the docs for ADFS where taken as I performed the steps. I could authenticate to Jenkins and retreive groups.

if viewing rendered markdown the image references do not work as GH is attempting to use the branchname from the origin not the fork. so in that case look at https://github.com/jtnord/oic-auth-plugin/blob/add-developer-docs/docs/developer/AD-FS/setup-test-instance.md for a rendered view.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.16%. Comparing base (c6bf1a8) to head (b48a299).
Report is 10 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #410      +/-   ##
============================================
- Coverage     74.18%   74.16%   -0.02%     
- Complexity      257      261       +4     
============================================
  Files            15       15              
  Lines          1007     1022      +15     
  Branches        145      147       +2     
============================================
+ Hits            747      758      +11     
- Misses          187      191       +4     
  Partials         73       73              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[mikecirioli]

wow, that is a lot of detail, thanks!

[PereBueno]

Great addition