PR feedback - binding IDs, simultaneos tracing to stderr

PR feedback - binding IDs, simultaneos tracing to stderr

Add bindingId parameters to traces. This is mostly in preparation for the .deps.json based ALC which will call into the host components and thus induce tracing.
Change the behavior to route tracing to both `stderr`/file and custom trace listener if both are enabled/registered.
Restructured the document given the new behavior to make it easier to read.
Small fixes.

Commit migrated from https://github.com/dotnet/core-setup/commit/ac9fcee14478afd9d3d14eab30f32d090ad4bb40