Calendar feature invite for mailing scripts

[aksahmitr]

TODO

Why?

It's better to send invites, adds a calendar entry + we won't need to allow them to enter everytime.

POA

• Add a feature which sends a calendar invite for the template which requires a google meet link. The mail body will become description this time.
  • Take care of the settings, they shouldn't see all the invited members, neither should be able to invite others. Also, other settings must be checked carefully
• If it doesn't have meeting link, then send normal mail (this code part already exist, just need to tweak when to execute).

[proffapt]

Read the issue again: #3

So the thing is like this, if one-to-one.py or bcc.py have a meet link then that should be a calendar invite. Explained more in the issue, have a read at it again.