Proxy configuration is extensible for custom metadata on routes, destinations etc

[alnikola]

There are several *Options types specifying parameters of different providers and policies like CookieSessionAffinityProviderOptions, ConsecutiveFailuresHealthPolicyOptions, TransportFailureRateHealthPolicyOptions etc. In the essence, they are part of the YARP configuration, but currently it's not possible to define them through the generic config provider mechanism. They can be set and changed through code only. There are some ad hoc workarounds to this issue created for some scenarios (e.g. health check policies), but there is a solid need for a well designed *Options configuration mechanism.

We should design and implement a proper *Options configuration subsystem.

[davidfowl]

Right, configuration metadata is a bit of a hack in how it gets manifested as a strongly typed object. We should have a system where configuration metadata is properly represented as a strongly typed object for consumption when various components are manifested.

[samsp-msft]

Clearing milestone so it can be re-triaged. I am not convinced that this is strictly needed now to be able to ship 1.0

[samsp-msft]

Duplicate of #1709