Embedding Projector: exit select mode onMouseUp (#6288)

* Motivation for features / changes
When Shift key is used to select points and is released before mouseUp,
UI does not exist selection mode after mouse is released, leaving a
permanent rectangular selection box with no way of panning.

* Technical description of changes
Reset orbit mode properly after mouse is released

* Screenshots of UI changes

* Detailed steps to verify changes work correctly (as executed by you)

* Alternate designs / implementations considered

Author: alicialics

tensorboard/plugins/projector/vz_projector/scatterPlot.ts

@@ -334,7 +334,7 @@ export class ScatterPlot {
   }
   /** When we stop dragging/zooming, return to normal behavior. */
   private onMouseUp(e: any) {
-    if (this.selecting) {
+    if (this.selecting || !this.orbitCameraControls.enabled) {
       this.orbitCameraControls.enabled = true;
       this.rectangleSelector.onMouseUp();
       this.render();