FR: Consider xcbeautify instead of xcpretty

[paulb777]

See https://github.com/thii/xcbeautify and https://twitter.com/steipete/status/1294269002454360064?lang=en

It might help with the cases we see occasionally of xcpretty hiding errors.

[paulb777]

Now at https://github.com/tuist/xcbeautify

[andrewheard]

Replacing xcpretty with xcbeautify has been started in #13983. See #13983 (review) or https://github.com/search?q=repo%3Afirebase%2Ffirebase-ios-sdk%20xcpretty&type=code for a list of remaining xcpretty uses in the repo.