runners: bench: Added best effort --list-probes, --list-case-probes, etc

Adds a set of flags to query the bench_runner for available probes:

- --list-probes       - List estimated probes
- --list-suite-probes - List estimated probes for each bench suite
- --list-case-probes  - List estimated probes for each bench case

What's fun though, is we don't actually know the bench probes at compile
time, since the BENCH_* macros take a C string. But we're already
preprocessing bench_*.toml with Python, so guessing what probes are
available is easy with a bit of regex:

  BENCH_(?:STOP|F?RESULT)\( *"((?:\\.|[^"])*)"

This does make the --list*probes flags best effort, but I think unlikely
to break in practice.

runners/bench_runner.h

@@ -116,6 +116,9 @@ struct bench_case {
     const bench_define_t *defines;
     size_t permutations;
 
+    const char **probes;
+    size_t probe_count;
+
     bool (*if_)(void);
     void (*run)(const struct lfs3_cfg *cfg);
 };