Add revocableTokenCacheDuration to resource proxy

[mike-marcacci]

If revocableTokenCacheDuration is configured, the proxy will cache the result of the introspection request for the configured number of seconds. Note that proxy instances do not share a cache, so a recently-revoked authorization may have different behavior between instances.

  /**
   * The number of seconds for which the proxy will cache the AuthX server's
   * token introspection response for a revocable token.
   *
   * @defaultValue `60`
   */
  readonly revocableTokenCacheDuration?: number;