Add typescript support for helper functions (#598)

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/frontend/pulls/598
Co-authored-by: konrad <konrad@kola-entertainments.de>
Co-committed-by: konrad <konrad@kola-entertainments.de>

tsconfig.json

@@ -0,0 +1,40 @@
+{
+  "compilerOptions": {
+    "target": "esnext",
+    "module": "esnext",
+    "strict": true,
+    "jsx": "preserve",
+    "importHelpers": true,
+    "moduleResolution": "node",
+    "allowJs": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "allowSyntheticDefaultImports": true,
+    "sourceMap": true,
+    "baseUrl": ".",
+    "types": [
+      "webpack-env",
+      "jest"
+    ],
+    "paths": {
+      "@/*": [
+        "src/*"
+      ],
+      "*": [
+        "types/*.d.ts"
+      ]
+    },
+    "lib": [
+      "esnext",
+      "dom",
+      "dom.iterable",
+      "scripthost"
+    ]
+  },
+  "include": [
+    "src/**/*.ts",
+    "src/**/*.tsx",
+    "tests/**/*.ts",
+    "tests/**/*.tsx"
+  ]
+}