perf test script: Add python script testing support

perf test script: Add python script testing support

Basic coverage of python script support from `perf script`.

Committer testing:

  $ perf test 'perf script python'
  107: perf script python tests                                        : Ok
  $ perf test -vv 'perf script python'
  107: perf script python tests:
  --- start ---
  test child forked, pid 595537
  Testing event: sched:sched_switch
  perf script python test [Skipped: failed to record sched:sched_switch]
  Testing event: task-clock
  Generating python script...
  generated Python script: /tmp/__perf_test_script.J4rWj.py
  Executing python script...
  perf script python test [Success: task-clock triggered param_dict]
  ---- end(0) ----
  107: perf script python tests                                        : Ok
  $

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Yujie Liu <yujie.liu@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>