[Feature Request] can you support the drag&drop by adding new component or directive?

### Existing Component
否

### Component Name
el-dragable

### Description
# Expected:
support the drag&drop new feature

I want to reorder the items in the `el-transfer` components。I notice that drag&drop was supported in some components like `el-table` & `el-tree`。So is it possible to seprate it as a new component or directive?

By the way, I've try using vuedraggable like below, but not works( *if I using v-for to create`.list-item`，it can be drag.But it's conflict with `el-transfer` data option*)
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