refactor: convert all components to composition API

src/App.vue

src/components/ContentView.vue

src/components/ImageView.vue

src/components/Loading.vue

src/components/Notification.vue

src/components/TreeView.vue

src/components/annotations/AnnotationIcon.vue

src/components/annotations/AnnotationsList.vue

src/components/annotations/AnnotationsView.vue

src/components/header/GlobalHeader.vue

src/components/header/Language.vue

src/components/header/Navbar.vue

src/components/header/PanelsToggle.vue

src/components/header/SoftwareInfo.vue

src/components/header/TitleBar.vue

src/components/header/Tools.vue

src/components/metadata/Actor.vue

src/components/metadata/CollectionMetadata.vue

src/components/metadata/ItemMetadata.vue

src/components/metadata/ManifestMetadata.vue