Shaders: Add Filter Width input to Bump node

This makes it possible to restore previous Blender 4.3 behavior of bump
mapping, where the large filter width was sometimes (ab)used to get a bevel
like effect on stepwise textures.

For bump from the displacement socket, filter width remains fixed at 0.1.

Ref #133991, #135841

Pull Request: https://projects.blender.org/blender/blender/pulls/136465

tests/python/cycles_render_tests.py

@@ -254,9 +254,12 @@ def main():
     # OSL tests:
     # Blackbody is slightly different between SVM and OSL.
     # Microfacet hair renders slightly differently, and fails on Windows and Linux with OSL
+    #
+    # both_displacement.blend has slight differences between Linux and other platforms.
 
     test_dir_name = Path(args.testdir).name
-    if (test_dir_name in {'motion_blur', 'integrator'}) or ((args.osl) and (test_dir_name in {'shader', 'hair'})):
+    if (test_dir_name in {'motion_blur', 'integrator', "displacement"}) or \
+       ((args.osl) and (test_dir_name in {'shader', 'hair'})):
         report.set_fail_threshold(0.032)
 
     # Layer mixing is different between SVM and OSL, so a few tests have