ProxyField: use Skinnable API to get current skin

SKINDATA is an implementation detail that should not be accessed from
this level.
2 jobs for fix/proxyfield_skinnable_api in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-TestRunner2

00:50:57

passed ERP5.UnitTest-TestRunner2

01:34:33