How to support multiple idp?

[coldcodefire]

hi guys, is it possible to support multiple idp? my goal is to make it work with Azure Ad and google auth ay the same time, and provide unique ACS path to idp side, which means at the idp side, it looks like one SAML SP. it can parse SAML assertion from Azure/Google in the same ACS path.
in current implementation, it seems SP is bond with an idp metadata. how can we expand this to multiple idp.

[gravgaard]

Interested due to #524