@graph-paper/core: create various overflow options for placeElement

[hamilton]

As it is now, the placeElement utility function has a few limitations for children that are potentially taller than the window height. We should add some options to accommodate the case where it might be taller.

A good first step would be to enable something like an overflow option for the utility. overflow would by default have flip (the current functionality), which if the floating element exceeds the window bounds, we flip the alignment or location so that it fits.

We need something like overflow: shift for some internal work, which would adjust the floating element so that it does not exceed the window edge.