[AOT] Improve suppressions on RouteEndpointDataSource

[JamesNK]

Doing API work in the Map* handlers to remove suppressions in the RouteEndpointDataSource.

[halter73]

Triage: We want to make sure that filtering a RequestDelegate works so AddFilter doesn't need to require dynamic/unreferenced code.

[captainsafia]

Triage: Verify if this work has been completed by James' work and if anything needs to be done.

[captainsafia]

Synced with @JamesNK and this can be closed.