Introduce new TreeView UI component

Key highlights:

- Written from scratch to cater specifically to privacy.sexy's
  needs and requirements.
- The visual look mimics the previous component with minimal changes,
  but its internal code is completely rewritten.
- Lays groundwork for future functionalities like the "expand all"
  button a flat view mode as discussed in #158.
- Facilitates the transition to Vue 3 by omitting the Vue 2.0 dependent
  `liquour-tree` as part of #230.

Improvements and features:

- Caching for quicker node queries.
- Gradual rendering of nodes that introduces a noticable boost in
  performance, particularly during search/filtering.
  - `TreeView` solely governs the check states of branch nodes.

Changes:

- Keyboard interactions now alter the background color to highlight the
  focused item. Previously, it was changing the color of the text.
- Better state management with clear separation of concerns:
  - `TreeView` exclusively manages indeterminate states.
  - `TreeView` solely governs the check states of branch nodes.
  - Introduce transaction pattern to update state in batches to minimize
    amount of events handled.
- Improve keyboard focus, style background instead of foreground. Use
  hover/touch color on keyboard focus.
- `SelectableTree` has been removed. Instead, `TreeView` is now directly
  integrated with `ScriptsTree`.
- `ScriptsTree` has been refactored to incorporate hooks for clearer
  code and separation of duties.
- Adopt Vue-idiomatic bindings instead of keeping a reference of the
  tree component.
- Simplify and change filter event management.
- Abandon global styles in favor of class-scoped styles.
- Use global mixins with descriptive names to clarify indended
  functionality.

tests/unit/shared/Stubs/TreeNodeStateAccessStub.ts

@@ -0,0 +1,45 @@
+import { NodeStateChangedEvent, TreeNodeStateAccess, TreeNodeStateTransaction } from '@/presentation/components/Scripts/View/Tree/TreeView/Node/State/StateAccess';
+import { TreeNodeStateDescriptor } from '@/presentation/components/Scripts/View/Tree/TreeView/Node/State/StateDescriptor';
+import { TreeNodeStateDescriptorStub } from './TreeNodeStateDescriptorStub';
+import { EventSourceStub } from './EventSourceStub';
+import { TreeNodeStateTransactionStub } from './TreeNodeStateTransactionStub';
+
+export class TreeNodeStateAccessStub implements TreeNodeStateAccess {
+  public current: TreeNodeStateDescriptor = new TreeNodeStateDescriptorStub();
+
+  public changed: EventSourceStub<NodeStateChangedEvent> = new EventSourceStub();
+
+  public toggleCheck(): void {
+    throw new Error('Method not implemented.');
+  }
+
+  public toggleExpand(): void {
+    throw new Error('Method not implemented.');
+  }
+
+  public beginTransaction(): TreeNodeStateTransaction {
+    return new TreeNodeStateTransactionStub();
+  }
+
+  public commitTransaction(transaction: TreeNodeStateTransaction): void {
+    const oldState = this.current;
+    const newState = {
+      ...oldState,
+      ...transaction.updatedState,
+    };
+    this.current = newState;
+    this.changed.notify({
+      oldState,
+      newState,
+    });
+  }
+
+  public triggerStateChangedEvent(event: NodeStateChangedEvent) {
+    this.changed.notify(event);
+  }
+
+  public withCurrent(state: TreeNodeStateDescriptor): this {
+    this.current = state;
+    return this;
+  }
+}