Add scripts in KNetCLI

[mariomastrodicasa]

Until now the tool needs to explicitly set the class to be used with ClassToRun command-line switch. A dotnet tool package can host more than one command: it is useful to create scripts (PowerShell, batch or sh) to execute the command directly:

KNetCLI -ClassToRun ConsoleConsumer --bootstrap-server SERVER-ADDRESS:9093 --topic topic_name --from-beginning

becomes

ConsoleConsumer --bootstrap-server SERVER-ADDRESS:9093 --topic topic_name --from-beginning

Originally posted by @mariomastrodicasa in #26 (comment)