Add versioned yaml files

[nshahan]

package:pedantic had a useful feature where it created versioned yaml files (see https://github.com/google/pedantic/tree/master/lib) that made adopting new versions easier.

This would allow different packages in a mono repo to choose which version of package:lints they are going to enforce via a dependency on a single version of the lints package (ie the Dart SDK).

As it is now, if there is an updated version of package:lints, all of the packages in a mono repo must be migrated to the new version at the same time.

[mit-mit]

As it is now, if there is an updated version of package:lints, all of the packages in a mono repo must be migrated to the new version at the same time.

Can you elaborate on this; I mean, even in a mono repo, doesn't each package in that repo have it's own pubspec, and thus can specify a different version?

[nshahan]

I meant a mono repo that forces a common set of dependencies pinned to the same version for all of the sub-packages. This is what the Dart SDK and Flutter repos do.