SAML SSO Service preferred binding type from IDP metadata

[codemasterover9000]

Expected Behavior

Allow The RelyingPartyRegistrations.fromMetadata*() methods to select a prefered binding type from the IDP metadata document.

Current Behavior

The RelyingPartyRegistrations.fromMetadata*() methods now pick the first binding type it comes across that is either redirect of post. So the order in which they appear in de IDP metadata document determines the used binding type.

Context

Due to security policies we need to use the POST binding if it is available. Currently implemented this by parsing the IDP metadata "manually".