Feat/file mail sender

[Molaryy]

Description

I added a new sharing method, by email. I used the nodemailer module to send emails containing the file that we want to share to other people that have a gmail account.

Changes include

• Bugfix (non-breaking change that solves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)

Checklist

• I have assigned this PR to myself
• I have added at least 1 reviewer
• I have added the needed labels
• I have linked this PR to an issue
• I have linked this PR to a milestone
• I have linked this PR to a project
• I have tested this code
• I have added / updated tests (unit / functionals / end-to-end / ...)
• I have updated the README and other relevant documents (guides...)
• I have added sufficient documentation both in code, as well as in the READMEs