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>

tests/unit/setup.ts

@@ -0,0 +1,16 @@
+import "./specs/mocks/matchMedia";
+import { config } from "@vue/test-utils";
+import { createHead } from "@vueuse/head";
+import { createI18n } from "vue-i18n";
+import en_US from "@/i18n/en_US.json";
+
+const i18n = createI18n({
+  legacy: false,
+  messages: { en_US },
+  locale: "en_US",
+});
+
+const head = createHead();
+
+config.global.plugins.push(head);
+config.global.plugins.push(i18n);