This commit adds the Zen Essentials Toolbar to the application. The toolbar is initialized in the `ZenEssentialsToolbar` class constructor by calling the `_initInitialLayout` method. The toolbar is inserted before the `vertical-pinned-tabs-container` element and consists of a scrollable container (`EssentialsToolbarItems`) for toolbar items. The toolbar also includes event listeners for mouse events and commands.
The commit also includes a code change in the `ZenSidebarManager` class where the `toggleEssentialsAccordion` method has been removed. This method was responsible for expanding and collapsing the `EssentialsToolbarItems` content based on the state of the header element.
These changes enhance the application by adding the Zen Essentials Toolbar and removing the unnecessary `toggleEssentialsAccordion` method.
This commit introduces a new "Zen Essentials" toolbar to the sidebar, providing quick access to frequently used features.
- The toolbar is based on the `PlacesViewBase` class and uses the `PlacesUtils` API to manage bookmarks.
- It includes a dedicated folder for Zen Essentials bookmarks, ensuring they're organized and easily accessible.
- The toolbar's visibility can be controlled by the `zen.essentials.enabled` preference.
- The toolbar supports drag-and-drop functionality for organizing bookmarks.
- The toolbar items are hidden if they are in another workspace.
- The toolbar supports hover interactions, highlighting the active bookmark on mouseover.
- The toolbar items can be opened in a glance by pressing `Ctrl`, `Alt`, `Shift`, or `Meta` depending on the user's preference.
- The bookmark toolbar automatically updates if the workspace changes.
