[CLD-6894] Add 60, 30, and 7 day reminder emails for Cloud Renewals (#25883)

* Add email notifications for Cloud Renewals

* Updates

* Updates

* Update app-layers

* make build-templates

* Add ability to set an env variable as a unix timestamp in s as the current date when getting DaysToExpiration

* Add a mechanism to ensure at least one admin receives every email

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Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Gabe Jackson <3694686+gabrieljackson@users.noreply.github.com>

server/channels/app/email/service.go

@@ -156,6 +156,9 @@ type ServiceInterface interface {
 	SendDelinquencyEmail60(email, locale, siteURL string) error
 	SendDelinquencyEmail75(email, locale, siteURL, planName, delinquencyDate string) error
 	SendDelinquencyEmail90(email, locale, siteURL string) error
+	SendCloudRenewalEmail60(email, locale, siteURL string) error
+	SendCloudRenewalEmail30(email, locale, siteURL string) error
+	SendCloudRenewalEmail7(email, locale, siteURL string) error
 	SendNoCardPaymentFailedEmail(email string, locale string, siteURL string) error
 	SendRemoveExpiredLicenseEmail(ctaText, ctaLink, email, locale, siteURL string) error
 	AddNotificationEmailToBatch(user *model.User, post *model.Post, team *model.Team) *model.AppError