src/ceph_osd, osd: Implement running benchmark during OSD creation

src/ceph_osd, osd: Implement running benchmark during OSD creation

The changeset implements the following:

1. Adds an option called "--run-benchmark" to the ceph-osd process to enable
   running the existing osd benchmark during the creation of the OSD but before
   it's added to the cluster. If the option is specified, the benchmark is run
   just after 'mkfs' is performed on the OSD.
2. A separate OSDBenchTest class is created that can be instantiated when the
   benchmark is needed to be run. The class has interfaces to perform precheck,
   prefill, run the actual randwrite test and do the cleanup. It also has
   interfaces to extract the metrics. The new class in used where applicable
   and maintains the existing behavior of the "bench" command.
3. The vstart.sh script is modified to run the benchmark and store the results
   for each OSD in ceph.conf. This currently prevents the execution of the
   existing benchmark during the OSD boot-up.

Signed-off-by: Sridhar Seshasayee <sseshasa@redhat.com>
Fixes: https://tracker.ceph.com/issues/71941