Add vitest, add json validation tests, fix broken json files (#566)

frontend/vitest.config.mjs

@@ -0,0 +1,11 @@
+import { defineConfig } from 'vitest/config'
+import react from '@vitejs/plugin-react'
+import tsconfigPaths from 'vite-tsconfig-paths'
+ 
+export default defineConfig({
+  plugins: [tsconfigPaths(), react()],
+  test: {
+    environment: "jsdom",
+    setupFiles: ["src/__tests__/setupTests.ts"]
+  },
+})