Moved `public const` declarations after `use` of traits
Moved `public const` declarations after `use` of traits

Ref: https://github.com/api-platform/core/pull/3402#discussion_r382033877

vincentchalamon/core,teohhanhui/api-platform-core,meyerbaptiste/core,teohhanhui/DunglasApiBundle,vincentchalamon/core,meyerbaptiste/core,jdeniau/DunglasApiBundle,soyuka/core,teohhanhui/api-platform-core,jdeniau/DunglasApiBundle,meyerbaptiste/core,soyuka/core,soyuka/core,api-platform/core,teohhanhui/api-platform-core,vincentchalamon/core,api-platform/core,meyerbaptiste/core,api-platform/core,teohhanhui/api-platform-core,soyuka/DunglasApiBundle,jdeniau/DunglasApiBundle,soyuka/core,vincentchalamon/core,api-platform/core,jdeniau/DunglasApiBundle