[FAB-10548] MockStub implements GetDecorations
[FAB-10548] MockStub implements GetDecorations

This commit adds GetDecorations support to MockStub and thereby
simplifies chaincode development that relies on the decorator
feature.

Change-Id: Ic8e7307be4ec14106583663d16e9bc4b770e4aca
Signed-off-by: Marcus Brandenburger <9e4a8a78686ac844c6932d1645f13454c19ba684@zurich.ibm.com>

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