trace: Better structure lib/trace and configure options

In the next commits, we'll add more tracing options for instrumentation and
specific tracer.

This rename follows a more meaningful naming standard. It also adds a catch
all "HAVE_TRACING" define that indicate in the code that we have tracing
enabled.

Part of #32910

Signed-off-by: David Goulet <dgoulet@torproject.org>