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.

src/presentation/components/Scripts/View/TheScriptsView.vue

@@ -42,7 +42,7 @@ import {
   inject,
 } from 'vue';
 import { InjectionKeys } from '@/presentation/injectionSymbols';
-import ScriptsTree from '@/presentation/components/Scripts/View/ScriptsTree/ScriptsTree.vue';
+import ScriptsTree from '@/presentation/components/Scripts/View/Tree/ScriptsTree.vue';
 import CardList from '@/presentation/components/Scripts/View/Cards/CardList.vue';
 import { ViewType } from '@/presentation/components/Scripts/Menu/View/ViewType';
 import { IReadOnlyUserFilter } from '@/application/Context/State/Filter/IUserFilter';
@@ -139,7 +139,8 @@ $margin-inner: 4px;
     padding-top: 15px;
     padding-bottom: 15px;
     &--searching {
-        padding-top: 0px;
+      background-color: $color-primary-darker;
+      padding-top: 0px;
     }
   }
 }