Add package-lock.json to source control

[seebees]

As of v3.18.2, as discussed in lerna/lerna#1998,
lerna will now force-add the package-lock.json file in each package
to git as part of the versioning workflow.
If these files are in our gitignore this will result in a confusing developer experience
and a failure of the lerna version command.

Further clearly identifying the version of all packages for a given commit will help with debugging.
package-lock.json was initially ignored because this is a library that is used by other developers
and the lock file is ignored when this package was published
and installed as a dependency.