Added check for git installation presence

[rustemd02]

Description

Added Git installation checking before attempting to clone a repository. Instead of silently opening an empty workspace when Git is not available, users now receive an alert message informing them that Git is required.

The implementation adds:

1. A new isGitInstalled() method that validates Git installation by running the "which git" command and checking its exit status
2. A validation check at the beginning of the cloneRepository() method that displays a user-friendly error when Git is not detected

Related Issues

• 🐞 Cloning Repository Without Git Installed Fails Silently #2031

Checklist

• I read and understood the contributing guide as well as the code of conduct
• The issues this PR addresses are related to each other
• My changes generate no new warnings
• My code builds and runs on my machine
• My changes are all related to the related issue above
• I documented my code

Screenshots