SAML SSO unit tests etc. (#455)

SAML SSO unit tests etc. (#455)

* Added two unit tests to SecurityUtilsTest to verify the found email address is correct
* Removed unused imports in SecurityUtilsTest
* Added unit tests for ServicesConfigReader while investigating DRYD-1702
* cleaned up leftover printlns in SecurityUtilsTest
* cleaned up imports in SecurityUtilsTest
* reorganized methods in ServicesConfigReaderImplTest
* refactored findUser method to make it easier to test and prepare it for deprecation of ReponseToken
* refactored some useful common code out of SecurityUtilsTest into AbstractSecurityTestBase
* refactored some of the SAML-object-creating utility methods
* made 'parse' methods public so they can be tested
* added unit test to check that 'identifier' probe assertions correctly pull out attribute values
* source cleanup: organizing imports, formatting
* added .mvn to .gitignore to ignore local, per-developer maven properties

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Co-authored-by: Anthony Bucci <abucci@bucci.onl>