Add mass-mail ability to club members, maybe with filtering

[marcus-sonestedt]

Is your feature request related to a problem? Please describe. Mass-emails sending via idrottonline.se doesn't have tracking, storage etc

Describe the solution you'd like Handling mass-notifications via the site and sengrid allows us to:

• customize send filter based on member info (age, competencies, licences, etc)
• track read/reach status
• store the emails for members to view
• add as notifications inside the site
• automatically parallel-post to facebook or other social media

Describe alternatives you've considered Keep using idrottonline.se. Works for now.

Additional context We don't have per-user notifications fully implemented yet.