More email preference options

This pertains to account-related email notifications, not email alert channels.

Currently, the only email preference option for account-related notifications is the weekly summary.

We have other account-related emails that are sent to all Admin and Owner roles:

• Status page open incident reminders

• Quotas hit (ex. AI invocations)

• Alert delivery failed (ex. webhook alert returned a failure status, so the alert wasn’t delivered)

• Private location unavailable

Not all Admins or Owners need these emails, and they get very noisy in large accounts. It would help to have notification options for these cases, so that users can turn off what they don’t need.