[FAB-11571] Improve peer gossip init
[FAB-11571] Improve peer gossip init

This patchset cleans up the peer start process by moving the gossip
service init process separately in a single method.

There will be several following-up patchsets to improve the entire start
process of the peer node. Keep each change small and focused.

Change-Id: Id59ba860e140f354991b3874c140993c39a190cb
Signed-off-by: Baohua Yang <3c1728ff36d27dfd99f7c17cb4c2fbaf35fbcddf@gmail.com>

manish-sethi/fabric-sidedb,muralisrini/fabric,xixuejia/fabric,hyperledger/fabric,manish-sethi/fabric,hyperledger/fabric,manish-sethi/fabric-sidedb,stemlending/fabric,binhn/fabric,manish-sethi/fabric-sidedb,muralisrini/fabric,stemlending/fabric,jimthematrix/fabric,stemlending/fabric,xixuejia/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,xixuejia/fabric,stemlending/fabric,muralisrini/fabric,manish-sethi/fabric,manish-sethi/fabric-sidedb,binhn/fabric,binhn/fabric,jimthematrix/fabric