Make StartupAnalysisBuilder-based analyzers work with WebApplicationBuilder

[halter73]

Today we have analyzers that warn for various misconfigurations of middleware, options and service registration all based on StartupAnalysisBuilder. We should make this work for applications using WebApplicationBuilder without a Startup class.

This is related to #34146. We want to address that with a new analyzer to verify middleware ordering for WebApplicationBuilder now that UseRouting()/UseEndpoints() is often implicit.

[JunTaoLuo]

This should probably be re-assigned.