[WP Event managers] Email sending to group organizers and members

[patriciabt]

From @peiraisotta document: Send bulk messages & emails to all organizers and members, by group, by role, by country (admin)

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On Meetup, event managers (Community team) have the ability to email all group organizers, and all members from a specific group or from all groups.

It is necessary to add at the manager level, in order for the events managers to be able to email them all, by group, by role, by country, by language, and also filter groups that have not organized an event in a given timeframe.

More filters could be useful, for example, all groups with/without upcoming events, all groups with upcoming online/in person events, etc (if you have more ideas, please add in the comments)

[mauteri]

This could be a feature at the network level that could fire an email to all organizers and available at a super admin level. Could have some filters for specific groups, countries (that would need to be a group setting if required), and language as well. We can have some analytics on groups that are frequently having events and ones that aren't.

Some of these features would come later as the first few groups on the platform would not be that many and should be able to be easily managed without all the features listed above.