Use CertificateGenerator in OIDC Wiremock tests

[sberyozkin]

Fixes #44761

Thanks @cescoffier for thinking about supporting creating chains, it was very easy for me to reuse the code.
I ended up using KeyStore API directly to insert certificate entries, as it is the only material that has to be inserted, but i did not hesitate to borrow the working code block for it from CaGenerator :-).

[quarkus-bot]

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[gsmet]

Were these tests in 3.15?

[sberyozkin]

@gsmet Yes, I'm not sure now how it will backport but I'll prepare a 3.15 specific backport, ping me please if it won't backport automatically

[cescoffier]

LGTM!

By the way, any API improvement ideas for the generator are more than welcome. I don't use that part often, so finding the best usability pattern is hard.

[sberyozkin]

Thanks @cescoffier Sure, I'll try to remove the direct use of KeyStore API, may take some time but I'm on it