close AF-1198, AF-1169, AF-1204, AF-1167, AF-1168
- **fix**: empty favorite cannot be dropped(AF-1198)
- **fix**: folder close animation has a unexpected delay
- **fix**: mount explorer's DropEffect to body to avoid clipping(AF-1169)
- **feat**: drop on empty organize to create folder and put item into it(AF-1204)
- **feat**: only show explorer section's action when hovered(AF-1168)
- **feat**: animate folder icon when opened(AF-1167)
- **chore**: extract dnd related `dropEffect`, `canDrop` functions outside component
using a [babel plugin](https://gist.github.com/pengx17/49e24ae8a5a609bdaff122ee8c679d1c) to transform all var(--affine-xxx) to cssVar
Some issues:
- tried ast-grep but it seems to be not easy to add imports conditionally
- current work does not work well with ts with types because babel will strip them out
CatsJuice