Support OAuth 2.0 Demonstrating Proof of Possession (DPoP)

[jgrandja]

This issue will add authorization server support for RFC 9449 OAuth 2.0 Demonstrating Proof of Possession (DPoP).

See the integration test requestWhenTokenRequestWithDPoPProofThenReturnDPoPBoundAccessToken() which demonstrates how to obtain a DPoP-bound access token.

spring-authorization-server/oauth2-authorization-server/src/test/java/org/springframework/security/oauth2/server/authorization/config/annotation/web/configurers/OAuth2AuthorizationCodeGrantTests.java

Line 989 in 779d87a

public void requestWhenTokenRequestWithDPoPProofThenReturnDPoPBoundAccessToken() throws Exception {

Related spring-security#16574