refactor: add eslint-plugin-vue && lint code (#976)

.eslintrc.js

package.json

src/App.vue

src/components/BackToTop/index.vue

src/components/Breadcrumb/index.vue

src/components/Charts/keyboard.vue

src/components/Charts/lineMarker.vue

src/components/Charts/mixChart.vue

src/components/DndList/index.vue

src/components/Dropzone/index.vue

src/components/ErrorLog/index.vue

src/components/GithubCorner/index.vue

src/components/Hamburger/index.vue

src/components/ImageCropper/index.vue

src/components/JsonEditor/index.vue

src/components/Kanban/index.vue

src/components/LangSelect/index.vue

src/components/MDinput/index.vue

src/components/MarkdownEditor/index.vue

src/components/PanThumb/index.vue