Add Expiry Indicator functionality with configuration and command set

- Implemented ExpiryItemService to manage expiry date logic for list items.
- Created ExpiryModels to define types and structures for expiry configurations and rules.
- Added RestError utility for handling API response errors.
- Developed ExpiryIndicatorFieldCustomizer to display expiry information in list views.
- Introduced ExpiryIndicatorCommandSet for extending expiry dates and managing settings.
- Added settings dialog for configuring expiry settings.
- Implemented localization support for English and German languages.
- Added TypeScript configuration files for project setup.
- Included TSLint configuration for code quality enforcement.

tsconfig.json

@@ -0,0 +1,28 @@
+{
+  "compilerOptions": {
+    "target": "es5",
+    "forceConsistentCasingInFileNames": true,
+    "module": "commonjs",
+    "jsx": "react",
+    "declaration": true,
+    "sourceMap": true,
+    "experimentalDecorators": true,
+    "skipLibCheck": true,
+    "typeRoots": [
+      "./node_modules/@types"
+    ],
+    "types": [
+      "es6-promise",
+      "webpack-env"
+    ],
+    "lib": [
+      "es5",
+      "dom",
+      "es2015.collection"
+    ]
+  },
+  "include": [
+    "src/**/*.ts"
+  ]
+}
+