feat: ListBox => ListView

[GeopJr]

Guess I'm really not meant to take a break from Tuba...

Anyway, ListView is the 1.0.0 blocker. This is yet another retry. Memory wise, it works. No matter how many posts you scroll down it will always be < 200 MB.

But that's because it patches GTK to limit it to 20 items recycler. We need to make our own one.

Main loop blocking wise, I did yet another round of profiling, the main things I can see is actions and binding. Obviously this still uses our messy binding and I don't think we will ever get over it, but we can at least try and do our best to optimize it. Moving away from GtkBuilder for status widgets might also help slightly. If we know that a timeline will only have a certain type of widgets we could attempt to optimize it further.