user_events: Add basic perf and eBPF support

Adds support to write out user_event data to perf_probe/perf files as
well as to any attached eBPF program.

Link: https://lkml.kernel.org/r/20220118204326.2169-5-beaub@linux.microsoft.com



Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>