fixes https://github.com/TryGhost/Team/issues/2924
This change adds a new bulk edit action for posts to update their
visibility. It also implements a modal to change the post access level
for multiple posts at once using this new API.
It also fixes a pattern that was used when modifying the Ember models in
memory. They previously were marked as dirty, this is fixed now. So when
going to the editor after modifying posts, you won't get a confirmation
dialog any longer.
- we previously used `@stdlib/utils` instead of the child package
`@stdlib/copy`, which is a lot smaller and contains our only use of
the parent
- this saves 140+MB of dependencies
- we keep ending up with multiple versions of the depedency in our tree,
and it's causing problems when comparing instances
- the workaround I'm implementing for now is to bump the package
everywhere and set a resolution so we only have 1 shared instance
- hopefully we can come up with a better method down the line
