Add forward/back buttons for daily notes

[propeeves]

I'd like to be able to navigate journal pages without navigating back to the full page list or using the search bar, so buttons that would link to the previous/next day would be very helpful.

This could also be extended to allow other pages to be linked together if not too difficult, maybe through a / command that would check if a current next/previous exists, then if not apply the proper metadata to enable it.