TypeScript support, allow missing index routes, and more

[karaggeorge]

Fixes #5
Fixes #6
Fixes #13
Fixes #23

Fixes part of #7

Overall updates:

• Rework positional arguments
  • Proper display for required/optional args (<required> vs [optional])
  • Add support for variadic args ([variadic..])
  • Respect positionalArgs order. It used to be random (or the order the keys in propTypes)
  • Add some validation for positionalArgs
• Fix the read-commands.js logic to ignore non-js files, not mess up deeply stacked commands
• Don't require every sub-command to have an index.js. If not, a default message rendering the other available subcommands is shown when "index" route is called
• Fix yargs sub-command logic
  • Nesting commands with different options, would add those options to the nested commands as well, now it's properly scoped
  • If a command is not defined, it would execute silently (no error), not it shows an appropriate list of other sub-commands
  • Fix for small-edge case where if a command does not accept positional args, but there are other available sub-commands, those are suggested, as the user probably miss-typed the sub-command (used to try and call the index route)
• Better TypeScript support
  • Didn't add much other than a few fixes in read-command.js other than Add support for typescript #20
  • Couldn't reproduce Add support for typescript #20 (comment)
  • Automatically adds minimal tsconfig.json if not present and there is a .tsx command (like Next.js does)
• Adds tests for new functionality

Note for TypeScript, I tried looking into generating args based on types instead of propTypes but I wasn't able to find something concrete with ast, since it can get really complex with something like:

type FirstProps = {
   text: string
}

type OtherProps = FirstProps & {
	someOtherArg: boolean
}

type Props = OtherProps

const Home = (props: Props) => <Text>{props.text}</Text>;

export default Home

If there's a good way to go about it I can add in a separate PR. From some research it seems like this might be useful: https://ts-morph.com/ but I wasn't able to get far (though I didn't spend much time on this)

Thank you for Pastel, I think it's an awesome way to develop complicated Ink APIs ❤️
Let me know if any updates are needed 😄

[vadimdemedes]

@karaggeorge Fantastic work, thank you so much!