crimson/osd: PG::repair_object() doesn't depend on MOSDOp anymore.

crimson/osd: PG::repair_object() doesn't depend on MOSDOp anymore.

Before this commit the method was depending on `MOSDOp::get_min_epoch()`
to start an `UrgentRecovery`. However, it seems `PG::get_osdmap_epoch()`
would be sufficient here as the very early stages of the processing
in `ClientRequest` ensure the PG fits the `get_min_epoch()` requirement.

In the classical OSD the counterpart code looks like below:

```
int PrimaryLogPG::rep_repair_primary_object(const hobject_t& soid, OpContext *ctx)
{
  // ...
  queue_peering_event(
      PGPeeringEventRef(
        std::make_shared<PGPeeringEvent>(
        get_osdmap_epoch(),
        get_osdmap_epoch(),
        PeeringState::DoRecovery())));

  return -EAGAIN;
}
```

In addition to the dependency minimalisation, the commits reformats
the code around `PG::repair_object()` to fit our guidelines.

Signed-off-by: Radoslaw Zarzynski <rzarzyns@redhat.com>