DEV: deprecate `invite.via_email` in favor of `invite.emailed_status`
This commit adds a new column `emailed_status` in `invites` table for
tracking email sending status.
0 - not required
1 - pending
2 - bulk pending
3 - sending
4 - sent
For normal email invites, invite record is created with emailed_status
set to 'pending'.
When bulk invites are sent invite record is created with emailed_status
set to 'bulk pending'.
For invites that generates link, invite record is created with
emailed_status set to 'not required'.
When invite email is in queue emailed_status is updated to 'sending'
Once the email is sent via `InviteEmail` job the invite emailed_status
is updated to 'sent'.
This change both speeds up specs (less strings to allocate) and helps catch
cases where methods in Discourse are mutating inputs.
Overall we will be migrating everything to use #frozen_string_literal: true
it will take a while, but this is the first and safest move in this direction
Do not send an activation email to users invited via email. They
already confirmed their email address by clicking the invite link.
Users invited via link will need to confirm their email address before
they can login.
