[NativeAOT] Handle event pipe environment variable configuration and output to file...

[NativeAOT] Handle event pipe environment variable configuration and output to file (#86656)

Updates to NativeAOT event pipe:
- Respect environment variable configuration
- Handle writing out to a file
- Enable tracing/eventpipe/config/name_config_with_pid test, which uses environment variable configuration to write directly to a file.