Reset rollback duration on subsequent commit confirm operation.

[hellt]

This proposal brings rollback reset functionality to the gNMI Commit Confirmed extension.

References to prior art

Any NOS compliant with RFC6241 Netconf Commit Confirmed capability supports resetting the rollback timeout on receiving new Commit Confirmed rpc:

A quote from the linked chapter:

If a follow-up confirmed operation is issued before the timer expires, the timer is reset to the new value (600 seconds by default).

/cc @dplore @kidiyoor