tracerrecord: add a log record class

tracerrecord: add a log record class

We use this class to register tracer log entry metadata and build a log
template. With the log template we can serialize log data very efficiently.
This also simplifies the logging code, since that is now a simple varargs
function that is not exposing the implementation details.

Add docs for the new class and basic tests.

Remove the previous log handler.

Fixes #760267