Move email templates and sraa config to disk

[phavekes]

Currently, the email templates used for emails to users are stored in the database during a push to https://{{ middleware_vhost_name }}/management/configuration. Since these change only rarely, we are moving them to disk.

Rationale:

• We've added the option to push the middleware config from manage (Add Openconext-Stepup config OpenConext-manage#627). We do not want the manage the email templates from there because they rarely change.
• This reduces the size of the push (in the event stream).

• The SRAA config is stored in parameters.yaml
• The email twig templates are stored in /config/openconext/email_templates/, one file for each template.
• Default twig email templates are included in the repo and the tars, which can be overwritten during (Ansible) deployment. Use the current templates included in devconf as default: https://github.com/OpenConext/OpenConext-devconf/blob/main/stepup/middleware/middleware-config.json#L7-L44
• The new versions of middleware uses the templates from disk, the values in the database are ignored. I.e. email templates are still allowed in the push and the database, but are ignored. This is required to make online red/green migration possible. Database schema change we will do later.
• Empty or missing templates in the database or config-push do not trigger error messages or warnings
• The new middleware version compiles the twig templates during cash warmup. Missing templates on disk or templates from disk that do not compile generate an error.
• Event replay must continue to work.
• Create / update tests

[pmeulen]

Templates on disk take precedence over the values in the database configuration

I think the new MW version can just ignore the email templates in the database, and always read them from disk. A backward-compatibility mechanism seems unnecessary here.

Empty or missing templates in the database or config-push do not trigger error messages or warnings

Yes, they should be allowed to be there for backward-compatibility reasons, but must be ignored. This means that updating the email templates using an API is no longer possible.

[phavekes]

Extra attention is needed for:

• Does every push add an event to the stream? Even if there are no changes?