feat(server): add configurable path prefix for path-based service differentiation

[Mortega5]

• Added the server.pathPrefix property to configure the path prefix for all resources (CCS, health, and metrics endpoints are not affected).

[wistefan]

The prefix also needs to be added to the well-known objects. The token endpoint in the .well-known/openid-configuration f.e. would be wrong

[Mortega5]

It is actually already covered: the prefix is set into v.host once, at verifier construction time in InitVerifier (verifier/verifier.go:397 and verifier/verifier.go:400).
Every field in GetOpenIDConfiguration — Issuer, AuthorizationEndpoint, TokenEndpoint, JwksUri (verifier/verifier.go:896-899) — derives from v.host, so they all inherit the prefix automatically, no per-field handling needed.

Verified end-to-end in a dev environment:

curl https://verifier.dev.xxxx.yyy/verifier/services/data-service/.well-known/openid-configuration

{
  "issuer": "https://verifier.dev.xxxx.yyy/verifier",
  "authorization_endpoint": "https://verifier.dev.xxxx.yyy/verifier/api/v1/authorization",
  "token_endpoint": "https://verifier.dev.xxxx.yyy/verifier/services/data-service/token",
  "jwks_uri": "https://verifier.dev.xxxx.yyy/verifier/.well-known/jwks",
  "scopes_supported": [
    "operator"
  ],
  "response_types_supported": [
    "code"
  ],
  "response_mode_supported": [
    "direct_post"
  ],
  "grant_types_supported": [
    "authorization_code",
    "vp_token",
    "urn:ietf:params:oauth:grant-type:token-exchange"
  ],
  "subject_types_supported": [
    "public"
  ],
  "id_token_signing_alg_values_supported": [
    "RS256"
  ]
}

did I miss anything?