Major frontend code cleanup (#452)

Many large changes, including:
- TypeScript enums are now string unions throughout
- Strong type-checking throughout the TS and Vue codebase
- Vue component props now all specify `as PropType<...>`
- Usage of annotated return types on all functions
- Sorting of JS import statements
- Explicit usage of Vue bind attribute function call arguments (`@click="foo"` is now `@click=(e) => foo(e)`)
- Much improved code quality related to the color picker
- Consistent camelCase Vue bind and v-model attributes
- Consistent Vue HTML attribute strings with single quotes
- Bug fix and clarity improvement with incorrect hint class parameters
- Empty Vue component objects like `props: {}` and `components: {}` removed

frontend/src/components/window/title-bar/WindowButtonsWeb.vue

@@ -1,5 +1,5 @@
 <template>
-	<div class="window-buttons-web" @click="handleClick" :title="fullscreen.state.windowFullscreen ? 'Exit Fullscreen (F11)' : 'Enter Fullscreen (F11)'">
+	<div class="window-buttons-web" @click="(e) => handleClick(e)" :title="fullscreen.state.windowFullscreen ? 'Exit Fullscreen (F11)' : 'Enter Fullscreen (F11)'">
 		<TextLabel v-if="requestFullscreenHotkeys" :italic="true">Go fullscreen to access all hotkeys</TextLabel>
 		<IconLabel :icon="fullscreen.state.windowFullscreen ? 'FullscreenExit' : 'FullscreenEnter'" />
 	</div>