Expose value of ValueNotifiers in Provider page

[kenzieschmoll]

I would expect to be able to see the value of a value notifier by default

I know this is possible by enabling the setting

but maybe there are certain classes we should special case for? ValueNotifier being one of them?
@rrousselGit @jacob314

[elliette]

Now that the Provider panel is a DevTools extension, I'm closing this issue in favor of rrousselGit/provider#883.