cleanup Draggable into ResizingAnchor (#989)

* Rename `Draggable` as `ResizingAnchor` since that is what it is used for and shouldn't be mistaken as a general draggable item

* Refactor `ResizingAnchor` to be much more smart about how it handles mouse movements. Allow it to know which direction the resizing should be in allowing it to produce exact resized values.

* Add event handlers for the min and max extents so that actions can be triggered when those extents are passed (in either direction)

* Add double click support

Signed-off-by: Sebastian Malton <sebastian@malton.name>

src/renderer/components/dock/dock.scss

@@ -14,10 +14,6 @@
       left: 0;
       bottom: 0;
       z-index: 100;
-
-      > .resizer {
-        display: none;
-      }
     }
   }
 
@@ -65,24 +61,7 @@
     }
   }
 
-  .resizer {
-    $height: 12px;
-
-    position: absolute;
-    top: -$height / 2;
-    left: 0;
-    right: 0;
-    bottom: 100%;
-    height: $height;
-    cursor: row-resize;
-    z-index: 10;
-
-    &.disabled {
-      pointer-events: none;
-    }
-  }
-
   .AceEditor {
     border: none;
   }
-}
+}