feat: #1342 - Window level tab (#1429)

* WindowLevel preset code changes

* Remove localStorage code as its already being saved and some small refactor on reducer/action

* Creating unit tests for preferences reducer

* Fix cypress after class naming change

* Make hidden false as default for tab components

* Remove addUserPreferences

* Small refactor to use commandsManager from getCommandsModule instead of getting it from App.js

platform/viewer/src/components/UserPreferences/WindowLevelPreferences.styl

@@ -0,0 +1,28 @@
+.WindowLevelPreferences
+  display: flex
+  padding: 20px 0
+  text-align: center
+
+  .wlColumn
+    display: flex
+    flex-direction: column
+    flex-basis: 0
+    flex-grow: 1.5
+    margin: 0 5px
+
+  .wlRow
+    display: flex
+    flex-direction: row
+    margin: 5px 0
+
+  .header
+
+  .preset
+    flex-grow: 0.5
+
+  .window,
+  .level
+    flex-grow: 1
+
+  .description
+    flex-grow: 2