Checkbox Support

[burnedfaceless]

Is your feature request related to a problem? Please describe.
My company uses this software to generate Excel reports. The latest reports that have been given to me contain check boxes. I noticed that Excel4Node does not have checkbox support.

Describe the solution you'd like
I would like checkbox support. I am a Node.js developer and I am willing to submit a pull request to implement this feature when I have some free time. Would anyone familiar with this repo be available as a resource for help? This would be the second pull request I have submitted.

Describe alternatives you've considered
An alternative is that we could generate the report and manually add the checkbox. I'm not going to do that yet. The report is 3 or 4 pages. For the page with checkboxes we will pull it from an older report done by hand and merge PDFs together to get by for now.

Additional context
None to add.