Ability to define the Db2 Connection Configuration via a CLI parm

[dennis-behm]

When having test and production instances of zAppBuild that need to connect the Db2 Metadatastore, the user has to be able to set various db2Connection.conf properties depending on the runtime environment.

Today, the user has to pass the override via the --propFiles or the --propOverrides option.

This property should be allowed to be defined via a cli parameter:

dbb-zappbuild/build-conf/build.properties

Lines 138 to 140 in a719842

	# Db2 connection configuration property file
	# Sample is povided at $DBB_HOME/conf/db2Connection.conf
	#metadataStoreDb2ConnectionConf=