build: switch from yarn to npm to manage js dependencies and move js contents to root

yarn v1 is being deprecated and starts to have some issues

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

src/filters/index.ts

@@ -0,0 +1,16 @@
+import nl2br from "@/filters/utils";
+import {
+  formatDateString,
+  formatTimeString,
+  formatDateTimeString,
+} from "./datetime";
+
+export default {
+  // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
+  install(vue: any): void {
+    vue.filter("formatDateString", formatDateString);
+    vue.filter("formatTimeString", formatTimeString);
+    vue.filter("formatDateTimeString", formatDateTimeString);
+    vue.filter("nl2br", nl2br);
+  },
+};