Support MIME type filters for ACTION_PICK_IMAGES

Client apps can filter by image/* or video/* mime types. To trigger
default PhotoPicker view with images and videos, no type needs to be
set.

Bug: 169737761
Bug: 185228105
Test: manual (see video on the bug)

Change-Id: Iad442622a46549f0d2865abd8f118acd0f4019f9
7 files changed