GD-511: Remove obsolete ProjectScanner tool (#513)

# Why
Since introducing `gdunit4-action` the tool `ProjectScanner` is
obsolete. The restore of project cache is done by:
```
    - name: 'Restore Godot project cache'
      if: ${{ !cancelled() }}
      env:
        GODOT_BIN: '/home/runner/godot-linux/godot'
      shell: bash
      run: |
        cd "${{ inputs.project_dir }}"
        echo -e "\e[94mStart of the recovery of the project cache ...\e[0m"
        $GODOT_BIN --path ./ -e --headless --quit-after 2000
        echo -e "\e[94mProject cache successfully restored.\e[0m"
```
or since Godot v4.2.2 by using `--import` flag to restore the cache

# What
Deleted the `ProjectScanner` tool