(demo) Remove bitmap resolution from asset library json

[ericrosenbaum]

NOT TO BE MERGED

this is just an illustrative PR for @fsih

This is a variation of #5460, but with the added change of removing the bitmapResolution field from all assets. This change should theoretically be safe (because the information in that field is redundant or unnecessary), but I noticed that it caused a bug:

• Add an SVG sprite from the library containing 2 or more costumes (e.g. "ball")
• click the "next costume" block
• note that the position of the sprite changes

My best guess is that this is caused by a line in the VM: https://github.com/LLK/scratch-vm/blob/develop/src/sprites/rendered-target.js#L712

basically, if the bitmapResolution is missing when you add a costume, it sets it to 2. A couple lines later, it divides rotation center by bitmapResolution. So for SVGs with a missing bitmapResolution, the rotation center gets incorrectly changed

[adroitwhiz]

I think it may be worth mentioning that the VM doesn't actually need to ever set the rotation centers after loading them initially, so the buggy VM code you mentioned can be completely removed.

[fsih]

Blocked on scratchfoundation/scratch-vm#2314

[fsih]

@ericrosenbaum I tested this out and I think it can be merged now!

[ericrosenbaum]

@fsih cool! this is actually on top of #5460, which is still in review, though, so it will have to come after that one

[chrisgarrity]

@ericrosenbaum should this just get closed now?