refactor(types): improve code readability & friendly to type hints (#1560)

Author: Pick

packages/runtime-core/src/vnode.ts

@@ -93,8 +93,7 @@ type VNodeChildAtom =
   | undefined
   | void
 
-export interface VNodeArrayChildren
-  extends Array<VNodeArrayChildren | VNodeChildAtom> {}
+export type VNodeArrayChildren = Array<VNodeArrayChildren | VNodeChildAtom>
 
 export type VNodeChild = VNodeChildAtom | VNodeArrayChildren