feat: 🍰 Send Notification E-Mail

Created by: Tirokk

🍰 Pullrequest

Send notification e-mail.

Issues

• fixes #4326 (closed)
• relates #4235 (closed)

Todo

• translate e-mail subject
• what is about Warning: *Email middleware* will not try to send mails. in notification middleware
• rename emailMiddleware to loggingMiddleware?
• setting for sending notification e-mails
  • @sushidave suggestions https://github.com/Ocelot-Social-Community/Ocelot-Social/issues/4326#issuecomment-899035067
• add text and link to e-mails to change e-mail notification settings
• test the seeding
• not all mentioned users are notified again if I change a post or comment. please check – moved to this issue #4680
• put all files to copy (potentially) in one folder for backend and webapp – moved to issue #4681
• write cypress test
• create new issue for more detailed settings: see https://github.com/Ocelot-Social-Community/Ocelot-Social/issues/4326#issuecomment-873359482
• db migration
• search for notice Wolle to clean up

Note Changes For Rebranding

• https://github.com/Ocelot-Social-Community/Ocelot-Social-Deploy-Rebranding/issues/24