improve email system

[halfcyan]

we need to be able to send out mass emails if we're going to have service disruptions or need to mitigate a vulnerability through updates (see current Januscape incident). currently we just... send out an announcement via discord. some stack users probably don't have discord and even more aren't in the fyra discord.

for this, i think we should have a template for service disruptions and for updates/vulnerability mitigation. we also need to be able to just select to send it to all users, all users with VMs, all users with billing set up, etc. instead of just having to use a CSV.

[ItsJamie9494]

I would suggest having a system where you have your status page, and when you add events to the status page, it can automatically send emails to users with the affected products purchased.