Story 429: Show watchlist photo CTA where photo absent

Only shows when PageImages is installed and images are not disabled.

Move styles from nearby to watchlist (nearby inherits watchlist styles
currently)

Note: Watchlist funnel is already setup from previous commit (see
I55ca707b41d49859a1f783fb5b7e8fb8179f4946)

Change-Id: I3d523664cf426b5053c13d1d1cf79cfc1b236181
Merge "Story 429: Show watchlist photo CTA where photo absent"