v2.0.0 refactor

[andrewchilds]

2.0.0 (2022)

Codebase refactor:

• Refactor codebase to use modern ES6 + ESM syntax
• Remove lodash, bluebird dependencies
• Replace colors dependency with chalk
• Upgrade all remaining dependencies to latest

Product simplification:

• Remove health command, which doesn't need to be part of the core app
• Remove unnecessary get, import, destroy, and reboot alias commands
• Remove AWS and Linode as providers - may revisit adding them back in if there is enough demand
• Rename var command to the not-reserved vars
• Rename the overly-general key command to sshkey
• Remove redundant overcast help [command] syntax
• Remove ability to store files and scripts in the .overcast directory, which is now focused on storing keys, variables, and cluster data
• Rename cluster create to cluster add, instance import to instance add.
• Removed clusters/variables caching, which fixes #48