Abstract base class for wrapping tools without direct tool exposure

An abstract base class is required for cases where external (native) tools need to be wrapped up without directly exposing the tool and it's parameters.

• Must be abstract and generic.
• Inherit from DefaultTask.
• Take an ExecSpec type as a parameter.
• Abstract method to create execution specification.
• Abstract method to configure execution specification.
• Protected method to run the specification via project.exec or worker API.
• Allow run environment to be changed,