integrate sprite editor with scene view

[suno lili So]

instead of the sprite editor and the scene view being totally separate ui elements, the scene view can respond to an "edit sprite" intent targeting a tile or entity by zooming in so the sprite fills most of the screen, but still displaying its surroundings (possibly excluding things that would render over it). then mouse events or equivalent can be used to edit the sprite live from within the scene

[suno lili So]

need to decide how editing sprites that aren't yet placed in the scene works

[suno lili So]

the basics of this are done as of af0af32, remaining steps are polish