osd: tiering: add proxy write support

Signed-off-by: Zhiqiang Wang <zhiqiang.wang@intel.com>
osd/ReplicatedPG: remove the peer_type assertion in eval_repop

When moving to proxy write, this assertion doesn't hold any more.

Signed-off-by: Zhiqiang Wang <zhiqiang.wang@intel.com>
osd: tiering: use proxy write in writeback mode

Signed-off-by: Zhiqiang Wang <zhiqiang.wang@intel.com>
osd/ReplicatedPG: set the RWORDERED flag for the promote copy-from op

Set the RWORDERED flag if there are proxy writes in fight when doing
promote copy-from op.

Signed-off-by: Zhiqiang Wang <zhiqiang.wang@intel.com>