[precheck] print the HTTP status as the failure reason when it's not 200

[rogerluan]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I see several green ci/circleci builds in the "All checks have passed" section of my PR (connect CircleCI to GitHub if not)
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

Any status code different than 200 would simply print the failing URL. But when that URL works fine for us, users, that's confusing. Showing explicitly what was the HTTP code received by fastlane's faraday script helps a lot identifying what the issue is.

Description

N/A

Testing Steps

To test this branch, modify your Gemfile as:

gem 'fastlane', git: 'https://github.com/fastlane/fastlane.git', branch: 'rogerluan-improve-precheck-failure-reason'

And run bundle install to apply the changes.

Here's a demo/sample:

[mollyIV]

That's a very welcome improvement 💯

Thank you!