Move PostKubeadmCommands into files

[BobyMCbobs]

To ease management of how an instance is provisioned, it would be nicer to have the shell commands as scripts read by CAM upon instance creation

[BobyMCbobs]

@hh suggests to stored the PostKubeadmCommands in .sharing.io.
That way, it's easier to manage and iterate on the instance set up.

This comes full circle and makes a lot of sense to me

[BobyMCbobs]

This was completed