OnlyOffice integration broken since refactor to make configuration dynamic

[SteffeyDev]

Description of the bug

I noticed that only office integration was broken in the latest version (8ece530). The onlyoffice plugin was modified in 9e142d5, so I pulled the commit before that (845c458) and confirmed that onlyoffice worked before that, so something in that commit must have broken onlyoffice. With the latest commit it only shows a blank page and is returning a 404 for /api/onlyoffice/iframe.

OnlyOffice does seem to be working in the demo site, not sure which commit that is running.

Step by step instructions to reproduce the bug

Using 8ece530

1. Modify the default config to add onlyoffice:

"features": {
    "office": {
            "enable": true,
            "onlyoffice_server": "http://localhost:8080",
            "can_download": true
        }
}

2. Login with the local backend
3. Create and open a .docx file

Observed behavior

The page for a .docx document is blank

Expected behavior

OnlyOffice should load to allow editing the .docx in the browser