This implements the OAuth2 code exchange step: after an auth code has been returned by the IdP through redirection, the client can use the obtained auth code to get an access token. If the request has a DPoP header, the returned token is bound to the DPoP key.

Co-authored-by: Vincent <Vinnl@users.noreply.github.com>

The mockJwk reference is unefined when setting up the mock, but the mockJwk() function is defined when *calling* the mock. Thanks @Vinnl !

Co-authored-by: Vincent <Vinnl@users.noreply.github.com>

The oidc module is independant from solid, so it should not depend on the core module, which is meant to be solid-specific. this implies some redundancy in the types implemented in both places, but that means that these types may evolve independantly, while still getting errors in case of incompatibility, which is a good thing.

The endpoint returns a token_type field, which can be used to verify that the token is of the requested type (Bearer or DPoP)

Importing jest requires to change the jest config, so all the modules should be updated.