Cycles/Eevee: unify depth of field settings for cameras

There is now a checkbox to enable/disable depth of field per camera. For Eevee
this replace the scene level setting. For Cycles there is now only an F-Stop
value, no longer a Radius.

Existing files are converted based on Cycles or Eevee being set in the scene.

Differential Revision: https://developer.blender.org/D4882

tests/python/eevee_render_tests.py

@@ -19,11 +19,9 @@ def setup():
     scene = bpy.context.scene
     eevee = scene.eevee
 
-    eevee.use_sss = True
     eevee.use_ssr = True
     eevee.use_ssr_refraction = True
     eevee.use_gtao = True
-    eevee.use_dof = False
 
     eevee.use_volumetric_shadows = True
     eevee.volumetric_tile_size = '2'