Extending dynamic routing capabilty for openid4vp

Currently, based on the `target_based_routing.yaml` file, for the `spidSaml2` flow the redirect is performed toward the SPID URL (f.e. https://localhost/Saml2/disco?entityID=https://idserver.servizicie.interno.gov.it/idp/profile/SAML2/POST/SSO&return=https://sso.exampleservice.it/Saml2/disco) , while for openid4vc the redirect involves invoking the backend API, which retrieves the credential but does not correctly propagate the entityId (since it is a generic openid4vp, https://localhost/Saml2/disco?entityID=openid4vp).

The idea is to instantiate and enable a dynamic mechanism that allows configuring the landing page based on the entityId. For example:
- openid4vp implemented with wwwallet → landing page: host/wwwallet-frontend/mypage
- openid4vp implemented with mycredential → landing page: host/mycredential/anotherpage
etc.

To replicate the scenario, it is sufficient to:
- configure force same-device with the test page
- start a wwwallet request for any credential and choose access via IT-Wallet
- stop in debug mode before the redirect

Moreover, the same-device flow, as currently structured, does not allow a browser redirect but always involves the instantiation of an application (similar to Slack login, which performs a browser-side redirect for credential input).