Move journal name appended to emails to templates

[joemull]

Describe the bug The journal name is appended to transactional emails right before they go out, rather than as part of the editable email templates.

https://github.com/BirkbeckCTP/janeway/blob/dce0e97c65671575ca77f75ea05fbad0430aa34a/src/utils/notify_plugins/notify_email.py#L23

This means:

1. It is not visible when composing an email, so the user might think they need to put the journal name in their email signature or in the body of the email, which would then be redundant information
2. It cannot be changed by the user in edge cases not anticipated by us
3. It makes testing emails a bit more difficult

This is a small thing, almost insignificant in itself, but for consistency with the rest of the email writing interface, it merits a change. In general we want to allow users to anticipate system behaviour and have reasonable control over it--especially when it is an email sent in their name. So, eventually, we want to make this part of the email template.

In addition to removing the line in notify_email above, this would involve a migration that adds {{ journal.name }} to templates as appropriate.

Janeway version 1.4.2