Display digital assets on the single artifact page & search results page

See #885 for more background information

• Show the main image of the artifact in the image viewing box (main image is photo, if no photo line art, if no line art detail photo, if not, then envelope photo, if not, detail line art, if not, then other rare photo type, SVG, then nothing)
• thumbnail must not be reduced in size on desktop and tablet view (it it way too small right now) #337 (closed)
• show links to flip through assets and to view 3d and rti shots as appropriate
• Check that the user has access to view before displaying ( check both artifact table are images public and the images table rights, but disable the second for now)

Possible dl assets:

• main photo
• detail photo
• envelope (photo)
• line art
• detail line art
• pdf
• rti surfaces (many)
• 3D render (many)
• SVG