[FAB-12553] add ability to add nodes in Raft tests
[FAB-12553] add ability to add nodes in Raft tests

Refactors Raft ordering service UT to support reconfiguration,
i.e. addition/removal of new nodes, introducing capability to
inject new chains into mocked network.

Change-Id: Ieb7f8973002ce2c70a59c7985aa09fc9fd0839ed
Signed-off-by: Artem Barger <6d127d713cb520aa658cf81ac2373d74ffc1958c@il.ibm.com>

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