Add VTag::into_children (#2638)

* Add `VTag::into_children`

Currently, VTag supports `children` and `children_mut`, but not `into_children` to complete the pattern. This is useful if someone wishes to destructively acquire the children of a VTag to reparent them to a different VTag.

* Repair broken doc comment on `VTag::children_mut`

* Remove spaces between functions

packages/yew/src/virtual_dom/vtag.rs

@@ -297,14 +297,22 @@ impl VTag {
     }
 
     /// Returns a mutable reference to the children of this [VTag], if the node can have
-    // children
+    /// children
     pub fn children_mut(&mut self) -> Option<&mut VList> {
         match &mut self.inner {
             VTagInner::Other { children, .. } => Some(children),
             _ => None,
         }
     }
 
+    /// Returns the children of this [VTag]
+    pub fn into_children(self) -> VList {
+        match self.inner {
+            VTagInner::Other { children, .. } => children,
+            _ => VList::new(),
+        }
+    }
+
     /// Returns the `value` of an
     /// [InputElement](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input) or
     /// [TextArea](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/textarea)