Fix build break (#702)

New version of grpc-js required 'fs/promises', which does not exist in
the particular version of Node 12 included in the
hyperledger/fabric-nodeenv:2.2 image. This was fixed in grpc-js v1.12.2.

This change includes npm-shrinkwrap.json files for the Node chaincode
used by tests to avoid any unexpected future dependency version
resolution changes.

Signed-off-by: Mark S. Lewis <Mark.S.Lewis@outlook.com>

.gitignore

@@ -5,7 +5,6 @@
 coverage
 docs/gen
 node_modules
-npm-shrinkwrap.json
 npm-debug.log
 yarn.lock
 tmp