Add support for auth_time Claim

**Description:**
The rule 13 of the ID Token Validation section [1] states,

> If the auth_time Claim was requested, either through a specific request for this Claim or by using the max_age parameter, the Client SHOULD check the auth_time Claim value and request re-authentication if it determines too much time has elapsed since the last End-User authentication.

The `auth_time` claim can be requested in the authentication request sent to the OIDC provider [2] by the OPTIONAL parameter `max_age`. Or else `auth_time` can be requested as an Essential Claim. In both of these scenarios, inclusion of `auth_time` claim in the ID Token is MANDATORY.

Going forward, this claim should be supported since it provides information the client could use to prevent attacks.

[1] - https://openid.net/specs/openid-connect-core-1_0.html#IDTokenValidation
[2] - https://openid.net/specs/openid-connect-core-1_0.html#AuthenticationRequest

No source files, tests, or entry points are named. Start by locating the ID Token validation and authentication-request handling in the Java SDK, then compare their behavior with the linked OpenID Connect sections. Done should mean the requested auth_time claim is supported according to those requirements, with coverage for the relevant scenarios.

Written by the indexing model from the issue text.