This is achieved by introducing graph Stage. We can split initial
rendering then from hooks when ready (like showing marked selections)
and the cleanup stuff.

useAff cached to aggressively. Added refs for path comparison (this also
adds a requirement of Eq path to useLoader now).

Also, removed lots of duplicated code in Loader.purs and unified to have
only one loader.

useMemo in useLoader does shallow object comparison -- probably this is
the reason.

Remove utility functions. They were reading refs constantly, pattern
matching on Maybe/Either. We can do everything in one go.

This still doesn't show up because I need GraphSideCorpus array from
somewhere, apparently.

Now the timeout for pause won't trigger if user quickly presses
stop/start FA.

Apparently, when graph rendering was fixed, it's not necessary to
refresh forceAtlas after sigma updates.

It's not needed now for testing the flickering.

It is enough to create a portal with that dummy ref-ed container.

This simplifies code and makes parentRef obsolete.

Turns out the issue was also at parent getting rerenders.
So the trick is that I added an empty div with ref for parent node and,
next to it, the Graph component pointing to that ref.
Graph component calls react's usePortal with that parent ref and a small
'createElement' div to hold sigma canvases.

Well, it still does a bit because parent keeps rerendering but we can
manage that.

Also, attempt to make automatic FA pause almost working.

I.e. no data is reloaded so there is less graph flickering.

Now state change doesn't refresh the graph.