tools/rtla: Create common_apply_config()

Merge the common bits of osnoise_apply_config() and
timerlat_apply_config().  Put the result in a new common.c, and move
enough things to common.h so that common.c does not need to include
osnoise.h.

Cc: John Kacur <jkacur@redhat.com>
Cc: Costa Shulyupin <costa.shul@redhat.com>
Link: https://lore.kernel.org/20250907022325.243930-4-crwood@redhat.com


Reviewed-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Crystal Wood <crwood@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>