fix(ui5-tree): make the height of tree adjustable (#2546)

FIXES #2545

Author: ilhan007

packages/main/src/Tree.hbs

@@ -7,6 +7,7 @@
     @ui5-item-click="{{_onListItemClick}}"
     @ui5-item-delete="{{_onListItemDelete}}"
     @ui5-selection-change="{{_onListSelectionChange}}"
+    class="ui5-tree-root"
 >
     <slot name="header" slot="header"></slot>
     {{#each _listItems}}

packages/main/src/themes/Tree.css

@@ -1,6 +1,11 @@
 @import "./InvisibleTextStyles.css";
 
 :host(:not([hidden])) {
-    display: block;
-    width: 100%;
+	display: block;
+	width: 100%;
+}
+
+.ui5-tree-root {
+	height: 100%;
+	width: 100%;
 }