perf testsuite: Add common output checking helper

As a form of validation, it is a common practice to check the outputs
of commands whether they contain expected patterns or match a certain
regular expression.

This output checking helper is designed to allow checking stderr output
of perf commands for unexpected messages, while ignoring messages that
are known to be harmless, e.g.:
  "Lowering default frequency rate to \d+\."
  "\d+ out of order events recorded."
  etc.

Signed-off-by: Veronika Molnarova <vmolnaro@redhat.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240702110849.31904-10-vmolnaro@redhat.com


Signed-off-by: Michael Petlan <mpetlan@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>