Core state experience is janky

[BenHenning]

It looks off that when you submit an answer it stays fixed. We may need to animate to fix.

[nikitamarysolomanpvt]

@BenHenning Could you please suggest expected result.

[BenHenning]

As to that, I'm not sure yet. This was primarily feedback from @seanlip, but I noticed it as well. We should be aiming to have a consistent experience with Oppia web, but it's not quite clear exactly what that means. I need to play a bit more with the app and see if I can figure out the differences.

My initial thinking is that we should enable recycler view animations when the state itself is changing, disable them when resetting the state (or maybe remove/re-add the state fragment w/ a fragment transition), and force the scroll position to 0 without the animation since that seems to be unexpected. I think I'll start with these and see how they feel.

[BenHenning]

See #1797 for another area where things actually seemed to get worse without a clear understanding why (image loading is sometimes very noticeably delayed). This might get better when we include images with topics when they're downloaded, though.