Use existingSecret for oidc secret as well

[webnotesweb]

Hello,

I have noticed that you have done recently refactoring of secrets handling and improving secret management.
Thank you for that! I am referring for example to these: #46 #17

So this current "issue" might not be considered issue/bug but rather security enhancement suggestion if I may.

If possible, can you please enable use of existingSecret as well for oidc secret just as you have done with PG for example.

Thank you very much for your time and help!

[oliverguenther]

Thanks for your report, indeed this is a good use case for OIDC as well, and I'll submit a PR when I find the time. We welcome outside contributions as well