Playground common

This package contains common code for the playground packages that doesn't fit in any other package. For example, the RecommendedPHPVersion is imported virtually everywhere and including it in any other specific package would result in a lot of circular dependencies.

Avoid adding new code to this package. @wp-playground/common should remain as lean as possible. It only exists to avoid circular dependencies. Let's not use it as a default place to add code that doesn't seem to fit anywhere else. If there's no good place for your code, perhaps it needs to be restructured? Or maybe there's a need for a new package? Let's always consider these questions before adding new code here.