Providing testing for current OAuth2 implementations

[poikilotherm]

Implementation task for epic #5974

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Testing needs to be provided before updating the OAuth2 lib ScribeJava to version 6.6.3, as currently 3.1.0 is used. Skipping multiple major versions is risky, although the Changelog does not name breaking changes.

Ideas so far: use WireMock to create canned responses for GitHub, Google and ORCID.

[poikilotherm]

Closing this for now as @pdurbin and I discussed on IRC the other day.
This should be picked up again once on Payara...