Use SmallRye Converters for JWT Claims conversions

[radcortez]

Conversion code from SmallRye Config was extracted to https://github.com/smallrye/smallrye-converters.

The plan is to implement a prototype to replace conversion code in SmallRye JWT and use the Smallrye Converters project.

This should help to address:
eclipse/microprofile-jwt-auth#100

[sberyozkin]

We have discussed it further with Roberto, and indeed the use of smallrye-converters looks very promising (see also the #212 WIP PR from Roberto).

The ultimate goal is to update all of smallrye-jwt conversion logic to use the various provided converters to convert claims to the custom injection target classes, for example, String to Long or String to Long etc.
Additionally, we already have all the non-standard complex claims represented as JsonObject.

The proposal is to do this migration to smallrye-converters in 2 phases.
Phase 1 - support the conversion of complex JsonObject claims only

1. Add smallrye-converters dependency and check Converter<JsonObject, T> when processing returning JsonObject claim values (I guess we'll need to pass the converters injected into JWTContextInfoProvider as a JWTContextInfo property)
2. add implementation/jsonb-claim-converter to support a JSONB based JsonObject to T converter
   (I can handle this step)

Users will chose either a provided JSONB converter or register a custom converter.

It will all have a very minimal impact. And in phase 2 we'll complete the whole migration.

CC @radcortez @darranl

[sberyozkin]

Of course we can try to do it in one go - but I guess it can be a less sensitive refactoring if we do in 2 iterations...

[sberyozkin]

I propose to tackle it for 3.3.0 - soon to be released 3.2.0 already has the MP-JWT 1.2.1 dependency update with a couple of minor jwt build issues to be fixed which is enough for 3.2.0