refactor: migrate from Jest to Vitest

It does so by:

- Installing vitest dependencies and removing the jest dependencies.
- Changing the test target in the Makefile to use Vitest.
- Changing the CI pipelines to use Vitest instead of Jest.
- Removing jest configuration from eslint.config.js and adding the
  vitest eslint plugin.

This commit also fixes some issues in the FetchProxy test suite.

Fixed: twpowertools:236
Change-Id: I6a6a636cd5e943194ff6b06c17a150537659d586
diff --git a/package.json b/package.json
index 8855a31..95806c1 100644
--- a/package.json
+++ b/package.json
@@ -32,18 +32,18 @@
   },
   "devDependencies": {
     "@babel/plugin-transform-modules-commonjs": "7.26.3",
-    "@jest/globals": "29.7.0",
     "@lit/localize-tools": "0.8.0",
     "@testing-library/dom": "10.4.0",
     "@types/chrome": "0.0.313",
     "@types/eslint__js": "8.42.3",
     "@types/node": "20.17.30",
+    "@vitest/coverage-v8": "3.1.1",
+    "@vitest/eslint-plugin": "^1.1.39",
     "copy-webpack-plugin": "13.0.0",
     "css-loader": "7.1.2",
     "eslint": "9.24.0",
     "html-webpack-plugin": "5.6.3",
-    "jest": "29.7.0",
-    "jest-environment-jsdom": "29.7.0",
+    "jsdom": "^26.0.0",
     "json5": "2.2.3",
     "mini-css-extract-plugin": "2.9.2",
     "path": "0.12.7",
@@ -53,11 +53,11 @@
     "sass-loader": "16.0.5",
     "style-loader": "4.0.0",
     "terser-webpack-plugin": "5.3.14",
-    "ts-jest": "29.3.1",
     "ts-loader": "9.5.2",
     "ts-node": "10.9.2",
     "typescript": "5.8.3",
     "typescript-eslint": "8.28.0",
+    "vitest": "^3.1.1",
     "web-ext": "8.5.0",
     "webpack": "5.98.0",
     "webpack-cli": "6.0.1",