Replaced most trivial checkboxes with Checkbox component

src/components/checkbox/checkbox.vue

src/components/emoji_picker/emoji_picker.js

src/components/emoji_picker/emoji_picker.scss

src/components/emoji_picker/emoji_picker.vue

src/components/post_status_form/post_status_form.js

src/components/post_status_form/post_status_form.vue

src/components/settings/settings.js

src/components/settings/settings.vue

src/components/style_switcher/style_switcher.js

src/components/style_switcher/style_switcher.vue