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>

vue-i18n-extract.config.js

@@ -0,0 +1,9 @@
+module.exports = {
+  vueFiles: "./src/**/*.?(ts|js|vue)",
+  languageFiles: "./src/i18n/en_US.json",
+  output: false,
+  add: true,
+  remove: false,
+  ci: false,
+  separator: ".",
+};