Specify main class, class path, and include dependencies when building jar

[Toastbrot236]

This fixes two bugs which previously, for me atleast, prevented java from properly executing the worker jar after building it using the maven CLI:

• The jar's manifest will now specify the main class so that java could find it
• The manifest will now also specify a class path (which java will use to find the dependency jars), and in a way where java will search for these dependencies in the /lib subdirectory. Additionally, maven will now be instructed to deploy these dependencies into /lib when building the worker, so that java could find them on runtime, preventing it from throwing NoClassDefFoundError.