Update Node.js versions to LTS 22 and 23 latest

[crramirez]

This pull request updates the Node.js version used in the setup and tests, and modifies the repository for shunit2 in the test setup script. The most important changes include updating the Node.js latest and LTS versions, and changing the shunit2 repository to a fork with additional features.

Node.js version updates:

• pengwin-setup.d/nodejs.sh: Updated NODEJS_LATEST_VERSION to 23 and NODEJS_LTS_VERSION to 22.
• tests/nodejs_latest.sh: Updated tests to check for Node.js version 23 instead of 22. [1] [2]
• tests/nodejs_lts.sh: Updated tests to check for Node.js version 22 instead of 20. [1] [2]
• tests/nodejs_n.sh: Updated tests to check for Node.js LTS version 22 instead of 20. [1] [2]

Test setup improvement:

• tests/install_shunit2.sh: Changed the shunit2 repository to a fork (AJIOB/shunit2) and checked out the AJIOB/add-time-stamps branch.