Hide taskbar on lockscreen

Add new animated float to disable taskbar
background value when keyguard is visible.

Fixes: 191857724
Test: Tested w/ and w/o bouncer for gesture + 3 button
Tested w/ IME pw on lock screen.

Change-Id: I2e1696fd25f4c170bfb2bc0694ccd644e453b1fe

quickstep/src/com/android/launcher3/taskbar/TaskbarKeyguardController.java

@@ -57,10 +57,6 @@ public class TaskbarKeyguardController {
         mKeyguardSysuiFlags = interestingKeyguardFlags;
 
         mBouncerShowing = bouncerShowing;
-        if (!mContext.isThreeButtonNav()) {
-            // For gesture nav we don't need to deal with bouncer or showing taskbar when locked
-            return;
-        }
 
         mNavbarButtonsViewController.setKeyguardVisible(keyguardShowing || dozing);
         updateIconsForBouncer();