refs https://github.com/TryGhost/Team/issues/2280
refs 9b0c21e0a2
As part of the email stability work, we added new `source` and `source_type` columns to `email` table, which allows us to store the email source information. The source for all existing emails before the stability work was always `html`, while newer emails will store `mobiledoc` or `lexical` directly.
While the `source` for all existing emails was populated with the `html` as part of above migration, we also need to store the right `source` for all new emails created till the feature is under a flag.
This change updates the current email flow to also store `source` with html data, so it can be used in future with new email service and allows removing old `html` column.
c5abef057c