**Why**:

- The specification for OpenID Connect RP-Initiated Logout 1.0 requires
  both HTTP `GET` and `POST` methods to be supported. See: https://openid.net/specs/openid-connect-rpinitiated-1_0.html#RPLogout

- Data sent using the `POST` method remains encrypted during transport in the
  browser and in web application logs, preventing leakage of sensitive
  information

**How**:

- The same endpoint shall be used, `/openid_connect/logout`, but the
  request data must be sent as part of the body and use form
  serialization (RFC 9110, sec. 9.3.3)

resolves https://gitlab.login.gov/lg-people/lg-people-appdev/protocols/openid-connect/-/issues/3

changelog: Bug Fixes, Security, Support POST for OIDC RP-Initiated Logout 1.0

…ed_examples