tracing: Add events to trace remotes

tracing: Add events to trace remotes

An event is predefined point in the writer code that allows to log
data. Following the same scheme as kernel events, add remote events,
described to user-space within the events/ tracefs directory found in
the corresponding trace remote.

Remote events are expected to be described during the trace remote
registration.

Add also a .enable_event callback for trace_remote to toggle the event
logging, if supported.

Link: https://patch.msgid.link/20260309162516.2623589-10-vdonnefort@google.com
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>