test(translate): migrate element-translate-ng to vitest

[spliffone]

Describe in detail what your merge request does and why. Add relevant
screenshots and reference related issues via Closes #XY or Related to #XY.

---

• I confirm that this MR follows the contribution guidelines.

[gemini-code-assist]

Code Review

The pull request successfully migrates the element-translate-ng project to use Vitest for unit testing, replacing Karma. This involves updating angular.json to use the @angular/build:unit-test builder, updating relevant package.json dependencies, and adjusting test files to use Vitest's vi.spyOn instead of Jasmine's spyOn. The tsconfig.lib.json and tsconfig.spec.json files have also been updated to reflect the new testing environment and exclude mock files from the library build. The README.md has been updated to reflect the change in testing framework. One area for improvement is to align dependency versioning in package.json with the established major version rule, as highlighted in the specific comments.

[github-actions]

[github-actions]

Documentation.
Examples.
Playwright report.

Coverage Reports:

• element-ng
• element-translate-ng

[chintankavathia]

We should keep headless default.

      "test": {
          "builder": "@angular/build:unit-test",
          "options": {
            "tsConfig": "projects/element-translate-ng/tsconfig.spec.json",
            "browsers": ["chromiumheadless"]
          },
          "configurations": {
            "browser": {
              "browsers": ["chromium"]
            }
          }
        }

[spliffone]

This isn't necessary, with environment 'CI=true' vitest will launch chromium headless