Split ObsDetails tablet landscape orientation in half instead of thirds

[kueda]

This will provide more space for photos and make the non-photo content more closely-resemble the phone layout.

[abhasinat]

Here is the updated design.

Key changes:

• [ ] change the width of the image area to be half the screen instead of a third
• [ ] Now, the image area functions exactly as it does on mobile, just with different dimensions. Photos should "fit" inside of the black rectangular area, and a user should be able to swipe left and right inside the left side of the screen to view additional photos in that observation.
• [ ] move the fave button to the bottom right corner of the image area, and add back in the carousel of dots indicating what photo a user is viewing