POC - Add usePersistentWatch flag to solrmonitor on top of the POC of permanent recusive watch PR

[patsonluk]

Description

This PR adds an extra usePersistentWatch flag to solrmonitor on top of the POC #58 .
Since the flag is default as false, it would revert to the old behavior of one-time, non recursive watch implementation of PRS enabled collection watching

This PR demonstrates:

1. The code change required to support such flag that flips between persistent watch/one-time watch . Take note that for one-time watch, we are also forced to use non-recusive watch, as there's no recursive option for one-time watch
2. The fetch count difference (as demonstrated in the unit test TestPRSProtocol) that persistent recursive watch does save on fetch count