Audit logs API extensibility/compatibility

[dyladan]

trafficstars

When we made the trace and metrics APIs we made some decisions that affected our ability to extend them in the future without breaking implementers. For example, adding a new span method breaks SDKs if it is not declared optional. Before the logs API is stable we should look into ways to improve this.

Below are some possible strategies

1. Emit events instead of calling SDK functions? Possibly using DiagnosticChannels although this is not available yet in web
2. Ensure we're using objects with types where possible instead of positional arguments