Update Firefox values for "browser.helperApps.neverAsk.saveToDisk"

[mdmintz]

Update Firefox values for "browser.helperApps.neverAsk.saveToDisk"

Some Content Types needed to be added so that those files are downloaded automatically without asking.
(See https://stackoverflow.com/a/34780823/7058266)
There were a few popular formats missing from the current list of Content Types there.

If you want PDFs to be downloaded (instead of displayed in the browser), you'll need to set external_pdf to True.
(That change, #3170, which makes Firefox consistent with Chrome, will be merged together with this ticket's change.)

[mdmintz]

This was resolved in 4.31.3 - https://github.com/seleniumbase/SeleniumBase/releases/tag/v4.31.3