Improve default vitest config for better watch mode (#349)

### Background

This PR enhances the test configuration for all function templates to improve the developer experience when running tests.

Issue : shop/issues-shopifyvm#755

### Solution

Updated all `vitest.config.js` files to include `forceRerunTriggers` configuration, which ensures tests automatically rerun when changes are made to either test fixtures or source code. This improves the development workflow by providing immediate feedback when making changes to either test data or implementation code.

The configuration now watches for changes in:
- `**/tests/fixtures/**` - Test data and fixtures
- `**/src/**` - Source code files

### Checklist

- [x] I have 🎩'd these changes
- [x] I have squashed my commits into chunks of work with meaningful commit messages

Author: achitojha

functions-cart-checkout-validation-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-cart-transform-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-delivery-customization-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-discount-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-discounts-allocator-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-fulfillment-constraints-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-local-pickup-delivery-option-generators-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-location-rules-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-order-discounts-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};

functions-payment-customization-js/vitest.config.js

@@ -1 +1,8 @@
-export default {};
+export default {
+  test: {
+    forceRerunTriggers: [
+      '**/tests/fixtures/**',
+      '**/src/**',
+    ],
+  },
+};