remove `yargs` from create-amplify

[0618]

Environment information

n/a

Description

We started using yargs in create-amplify since https://github.com/aws-amplify/amplify-backend/pull/960, but it's only used in one place, which might not be necessary.

We should try removing it.

edit:

The solution needs to be discussed.

Option 1 (@sobolk ): refactor to move yargs to top level script

Option 2 (@edwardfoyle ): move all of create-amplify into an amplify setup subcommand and then create-amplfiy is essentially just an alias for npm install @aws-amplify/backend-cli && npx amplify setup . That way all of our arg parsing logic is consolidated into @aws-amplify/backend-cli

[sobolk]

👎 we'll loose help output if we do.