doctor: show required versions

[lucasbento]

Summary:

This PR is related to #694 and it:

1. Shows the required current and required version for a failed health check;
2. Changes the wording from to fix all issues to `to try to fix all issues;
3. Fixes a problem where if you type a character not recognised on the usage it just doesn't listen to the correct characters anymore;
4. Puts the description content below the health check name rather than on the right side.

Preview

Test Plan:

Run doctor.

[thymikee]

Shows the required current and required version for a failed health check

I can see how that looks nice with colors, but please notice that this command will be ran in case of issues, likely by inexperienced RN users. We need to be more descriptive than showing an arrow. I'd rather like to give it a human-readable text like "We found vX, however we need vY".

Puts the description content below the health check name rather than on the right side.

I'm not a fan of this change. Initially when I read the "Watchman" and its description below, I was confused where it belongs. Let's either keep it in the same line (why moving it? it fits nicely even with version), or indent it one level or do something else.

How about this UI:

Android
  v ANDROID_HOME
  x Android SDK - Required for building and installing your app on Android devices.
    - found at: <dim>/Users/user/Android/SDK
    - version:  <red>v23.0.1
    - to fix: 	<bold>upgrade to v26.0.0. Here's how: <dim link>
  x Android NDX - description
    - version: 	<red>not available
    - to fix: 	<bold>install v19.0.0. Here's how: <dim link>

[thymikee]

shouldn't we require versions and ranges from all health checks?

[lucasbento]

Some of them are not based on comparing versions, just checking if they are there or not (e.g. ios-deploy and cocoapods).

[thymikee]

Thank you, code LGTM! Doctor starts to shape up :D. Let's iterate on the UI, to be a bit more approachable for beginners, maybe by structuring the output in a easy-to-follow important stuff way and being descriptive in messaging

[lucasbento]

@thymikee: cool, thanks for the review.

The approach you suggested looks good, I'll see what I can do!

[lucasbento]

@thymikee: what do you think about this?

A few points related to your proposal:

• I'm not sure if the path to the software/lib is useful, perhaps it's just more info clogging the UI;
• We currently don't have a way to show a to fix part on this step as it's shown only after the user tries to fix it all.

[thymikee]

Looks good!

[lucasbento]

@thymikee: pushed :)

[Rainsho]

What if I forgot to install build-tools when using sdkmanager manually? Here will throw an Cannot read property '0' of undefined error, instead of telling me to install build-tools through sdymanager "build-tools;29.0.0".