CB-5592 Android - Add MIME type to Intent when opening file:/// URLs

To avoid the "No Activity found to handle Intent..." error.
(cherry picked from commit 176890f30599fc72d33eeb1f5daa1fa5e6358325)
CB-5592 Add a comment explaining why we set MIME only for file:
(cherry picked from commit 6163f17aeb901d9ff6b3df68666b2efedcd0162e)
Backport CB-5592 to open file:///