Performance improvements for Client Certificate auth

[analogrelay]

• Evaluate revocation list caching (Windows does it by default but other OSes?)
• Caching validation results (could use the per-connection caching stuff in Kestrel)

[blowdart]

@Tratcher has ideas around using the connection feature.

You'll still need to validate the expiry on each request however.

[Tratcher]

Kestrel has a connection.Items feature that we use for caching in NegotiateAuth.

aspnetcore/src/Security/Authentication/Negotiate/src/NegotiateHandler.cs

Lines 374 to 375 in 18cb57a

	return Context.Features.Get<IConnectionItemsFeature>()?.Items
	?? throw new NotSupportedException($"Negotiate authentication requires a server that supports {nameof(IConnectionItemsFeature)} like Kestrel.");

CertAuth wouldn't want to rely on this directly since we need cert auth to work with all servers, but we should be able to put in a basic cert auth caching abstraction service and do a simple implementation for Kestrel. Other implementations could use MemoryCache?

[blowdart]

A bounded memory cache obviously :)