Apply ObjectPostProcessor to the filter in WebAuthnConfigurer

[kse-music]

Closes gh-16369

[rwinch]

Thanks for the PR @kse-music However, I'd like it split into two features even though it is in a single ticket. This helps us to track changes more accurately.

One of the pull requests would focus on configuring PublicKeyCredentialCreationOptionsRepository. I'd prefer to have a bit more first class support for configuring PublicKeyCredentialCreationOptionsRepository. The configuration should have an explicit property for PublicKeyCredentialCreationOptionsRepository. If it is set, then it should be used. Otherwise, if there is no value set on the DSL, it should look for a unique Bean of type PublicKeyCredentialCreationOptionsRepository. If it exists, then, it should be used.

For the other pull request, it would allow configuring HttpMessageConverter<Object> through the DSL only. This is important because serialization/deserialization should be explicit to avoid accidentally opening up a deserialization vulnerability.

I'm going to close this and if you are able, I'd love to see two PRs split up in that way.