Move Config read/write into cli

[NotWoods]

Moves functions for reading/writing Config into the cli, since none of them are used in core. check() has been removed since its no longer used.

Also added a path parameter so a prompt could be added to allow custom config paths.

Core Config is now just a data class, so perhaps it should be changed to an interface.

[PEConn]

I'm happy with adding the path, unsure about whether methods for reading/writing the config should be part of the core library even if they're not used there. @andreban thoughts?

[andreban]

Functions to load and save the config would ideally be part of the library.

The section of code that tries to load a config from a file and asks users for config information if it fails (loadOrCreateConfig) and createConfig should be part of the CLI.

We may also want to add Config#serialize(): string and Config#deserialise(config: string): Config to make it easier for developers who'd like to save a Config to a database, for instance.

[andreban]

We should move save and load methods into core.

[andreban]

LGTM, Thank you!