Break apart sync command

[LPGhatguy]

tarmac sync is very complex. It's effectively the only command in Tarmac.

It would be useful to create smaller commands that contain each auxiliary piece of functionality, which should help us manage complexity.

• tarmac sync will just sync assets to the Roblox cloud
  • The --target parameter should be removed.
• tarmac dev will just sync assets to a local installation to work on in development mode
• tarmac generate-cache, pitched in Option to populate a cache directory #15, will generate a cache from the current state
• tarmac create-path-map (Add create-cache-map subcommand #38) will write a map of all assets managed by Tarmac
• tarmac verify-synced will validate that the project is in sync with the Roblox cloud
  • Can we verify moderation status in this subcommand?
  • Can we verify that assets are uploaded to the correct group here?