[feature request] Allow Internal PDF viewer to be used by File Explorers.

[imshivlok]

Hey,
This has been a great browser so far.
I see that you've added a new PDF viewer recently, which lets the user open downloaded PDFs within the app itself.
It would be nice to see this PDF viewer available system-wide. For example, opening a PDF from WhatsApp, opening a PDF from the file manager, etc.
This would get rid of the "Google Drive" for me.
Thankyou for the wonderful browser!