Move TokenRelayGatewayFilterFactory from spring cloud security to spring cloud gateway with additional automatic token refresh

[boal]

The class TokenRelayGatewayFilterFactory contains a deprecation comment (see https://github.com/spring-cloud/spring-cloud-security/blob/bc697b580edde87cfa11bedb68ade0258bc84c94/spring-cloud-security/src/main/java/org/springframework/cloud/security/oauth2/gateway/TokenRelayGatewayFilterFactory.java#L32) which states that this class should be transferred to spring cloud gateway in next major release. For the transfer, it would be very helpful if an enhancement was implemented.

The enhancement comprises adding automatic token refresh to class TokenRelayGatewayFilterFactory as explained in issue spring-attic/spring-cloud-security#175.

The issue already provides a solution (https://gist.github.com/tschlegel/62418600e04498d8c1db67ce5e1f17eb) from @tschlegel which works very well.

[spencergibb]

This was already done in 2f00ee8ed9ddecdda90c5d370ef30bcb252f05e5e782ee1e1125188c3a3698e4