Recognise file:// links in notes (deep-link to local files)

When typing or pasting a link starting with file:// into a note, Bullet should recognise it as a clickable link that opens the file in its default OS app. Use case: people working with lots of local PDFs and documents want to deep-link to them from notes without uploading them to cloud storage first. Current workaround is linking to iCloud/Drive web versions, which is an extra step and requires making files shareable. Most relevant on the desktop web app.