Fix browser tab name displaying "app.title.undefined" after refresh

When refreshing the browser window while navigated to a Document, the browser tab title momentarily displays "app.title.undefined - Nuxeo Platform" before updating with the Document name (followed by " - Nuxeo Platform").

Steps to Reproduce:

1. Navigate to a Document in Web UI
2. Refresh the browser

Expected behavior: until Document metadata is loaded, browser tab name is shown as "Nuxeo Platform" (as seen in LTS 2019)

Actual behavior: momentarily, browser tab name is shown as "app.title.undefined - Nuxeo Platform" before updating to show the Document name followed by " - Nuxeo Platform"

(see attached video for reference)