Ckeditor5: Incorrect versions of ckeditor5-* packages in devDeps

[Reinmar]

See https://github.com/ckeditor/ckeditor5/blob/af4d33e619281c48c35ab2d0a02a20527db2a50a/packages/ckeditor5-widget/package.json#L34

This is not a serious problem as this is a dev dep, but it's worrying why this happened. 

I guess with the new versioning rules this has very little chance to happen, but we should check after the release that everything was bumped just in case.

[pomek]

The package is defined as dependencies and devDependencies:

https://github.com/ckeditor/ckeditor5/blob/55d9f6091efd7d1b298390a80d0755fce2d4a19d/packages/ckeditor5-widget/package.json#L14
https://github.com/ckeditor/ckeditor5/blob/55d9f6091efd7d1b298390a80d0755fce2d4a19d/packages/ckeditor5-widget/package.json#L34

The script that "updates dependencies" bumps the version of packages in the specified order: dep, devDep, peerDep:

https://github.com/ckeditor/ckeditor5-dev/blob/81054e00f04815582a39de973f04a9c091fc299d/packages/ckeditor5-dev-env/lib/release-tools/utils/updatedependenciesversions.js#L21-L27

We have two solutions/tasks here:

1. updateDependenciesVersions() function should update everything (not only the first match)
2. Remove duplicated items. dependencies is more important than devDependencies and I guess, npm will install the package in the version specified in the first object.

However, our dependency linter could look for duplicated items between deps and devDeps and report them.

[Reinmar]

However, our dependency linter could look for duplicated items between deps and devDeps and report them.

I think we should prevent issues, not fix them when they exist. So, linter prevents anything incorrect getting into the codebase and I'd be for adding this check to it.