Init new package from command line

[paupino]

Create an --init command to help create a new psqlpack project.

[paupino]

• init publishprofile and init publish_profile - create default publish profile (.publish extension?)
• init project - create default project file
• init sample or init demo or init example - create a sample project

[paupino]

I'm going to settle on using new as a subcommand whereby:

• project creates a new folder with a default project file and publish profile.
• publishprofile creates a new publish profile

In the future we could also add things like schema, table etc...