Arnold 7.2.2 support

[JenusL]

This update brings support for the following new Arnold features from Arnold 7.1.4 to 7.2.2

• Global light sampling (v7.2.1 and v7.2.2)
• New parameter enable_sky in physical_sky to disable the sky. (v7.2.0)
• New Autobump for shadow and SSS rays in Arnold Parameters (v7.2.0 and v7.2.2)
• New distance shader (v7.2.1)
• New wset and uvw_matrix parameters added to uv_transform (v7.2.1)
• The set_transform operator can now handle motion blur correctly. (v7.2.1 and v7.2.2)

SItoA improvements unrelated to Arnold version

• A lot of operators had their inputs exposed to be linked. That was not supported and has now been fixed.

Incompatible / Behavior changes

• The global setting Use Autobump in SSS is now removed. If you had it enabled in an old scene, you now need to enable it on the objects Arnold Parameters instead to get the same look.
• SItoA versioning is now using four numbers like all other *toA plugins.

Bugfixes

• None

Build system fixes / changes:

• Updated Autobump in SSS test (0126) to use the new autobump settings.
• Updated operators test (0268) to use motion blur.

Passes testsuite.