`yarn add pkg` should default to the version used in the other workspaces instead of latest

Do you want to request a feature or report a bug?

This is an enhancement.

What is the current behavior?

Running yarn add pkg in a workspace will install the latest version of pkg.

What is the expected behavior?

Running yarn add pkg in a workspace should use the same version as the other workspaces if possible in order to deduplicate them.

This is a potentially confusing change so we can discuss it there.