Refactor

[gilesknap]

This refactors the code into a fashion that is more appropriate for adding an interactive TUI.

• A new base class Commands provides the common command implementations.
• K8sCommands derives from the above and provides K8S specific implementations.
• LocalCommands derives from Commands and provides local docker/podman implementations.
• These classes are initialized with context that is constant like namespace but not with any other args
• Monitor is now given a Command class so it can call the functions in blissful ignorance of the underlying implementation.
• global exception handling is added to the typer cli and will report if a function is not implemented for the current environment

Frankly, I wrote this inside out initially and this is how it should have been done. The unit tests were a great help in making these changes.