[3.13] (Konnect only) Support for JWT Signer plugin

## Jobs to be done (optional)
As a Konnect user, I want access to the JWT Signer plugin.

## Definition of done
Update https://developer.konghq.com/plugins/jwt-signer/ with konnect support.

## Information
https://konghq.aha.io/features/RUN-96

## Due date (optional)
3.13 GA

## Size

XS