Moving Faker out of Standard.Test API

[JaroslavTulach]

Pull Request Description

• another fix for Clean Standard.Test API up #12456
• Faker is only used in test/Benchmarks
  • hard to imagine such generators as a generic purpose API
• hence moving the class out of Standard.Test API

Important Notes

• this change as already been proposed as part of Make Standard.Test pending field lazy #14536
• but it got backed out to not block progress on the other aspects of Make Standard.Test pending field lazy #14536
• now proposing it again in its own PR

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• All code follows the
  style guides.
• Unit tests and benchmarks continue to execute well

[jdunkerley]

As discussed previously I want the Faker API in the standard libraries and part of Standard.Test makes sense to me.

It is useful to be able to create mock data and use it within workflow scenarios