Project structure: introduce token-spi module

[ndr-brt]

Feature Request

As reported in #1832 , common/token-generation-lib and common/token-validation-lib contain interfaces that are actually implemented by extensions, so probably they deserve to be put in an spi module.

This new token-spi module will contain:

• JwtDecorator
• JwtDecoratorRegistry
• TokenValidationRule

As these 3 interfaces are being implemented by different modules

Which Areas Would Be Affected?

common, spi

Why Is the Feature Desired?

cleanup

Solution Proposal

Type of Issue

cleanup

Checklist

• assigned appropriate label?
• Do NOT select a milestone or an assignee!

[bscholtes1A]

maybe should be more generic than token-spi.

I would prefer to call it security-spi, containing a subfolder token-spi.

As detailed in #1357 there are some duplicated stuff between the token validation/generation libs and what some code in DID identity core (key wrappers,...)

Thus this would be a good opportunity to later put this common stuff into this security-spi module.

[ndr-brt]

@bscholtes1A I'm on this but to me is not that clear which should be the right design to follow.
I will create a PR to accomplish this specific issue, better relate to the other for the refactoring you proposed.