Plugin: Social media feed

Is your feature request related to a problem? Please describe.
As a Janeway Press Administrator, I would like to give the Press Journals and Repositories the option to post an automated feed of new publications to social media services, such as Twitter and Mastodon.

Describe the solution you'd like
Create a plugin at the Press level for which one can enable social media feed support to each Journal or Repository.

The plugin main page should include a list of all journals and repositories in the system, each linking to a sub-page to configure social media feed support for the corresponding journal or repository.

On the each social media page, the Admin should be able to configure settings for each service: credentials, post template.

For journals, there should be an option to only post new Issues, or new Articles.

For repository, there should be a notice that a new social media post will be made when a new repository item is published (not accepted, in case the publish date differs).

No files, tests, or entry points are named. Start by locating the Press-level plugin system and the Journal and Repository publication workflows, then identify how existing plugins store credentials and settings. Done means administrators can configure services and templates per journal or repository, with the specified publication triggers producing social media posts.