Update Node.js to >=20.0 and Yarn to 4.9.3 for Varbase AI to align with Drupal Core with GitLab CI/CD

Problem/Motivation

Following with:
Update engines yarn to >= 4.9.3 and packageManager to yarn@4.9.3 in the Varbase Project template #307

Proposed resolution

Change to

  "license": "GPL-2.0-or-later",
  "private": true,
  "engines": {
    "yarn": ">= 4.9.3",
    "node": ">= 20.0"
  },

and

  "packageManager": "yarn@4.9.3"

• Add the .yarnrc.yml file.
• Update dependencies to follow with Drupal Core package.json file
• Update the yarn.lock file.
• Add .cspell.json file
• Check this link to see how to switch yarn to 4.9.3 or 4.9.4 in your local.
• Add .gitlab-ci.yml file with basic build and linting

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release varbase-10.1.0-beta1, varbase_ai-2.0.5

Varbase update type

• ✅ No Update
• ➖ Optional Update
• ➖ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• [#3549184] chore(tooling): Updated Node.js to >=20.0 and Yarn to 4.9.3 for Varbase AI to align with Drupal Core with GitLab CI/CD