dxvk_helper(): re-factor to: helper_dxvk_d9vk()
dxvk_helper(): re-factor to: helper_dxvk_d9vk()

 * use a joint: helper_dxvk_d9vk() function to support dxvk and
   d9vk verbs
 * helper_dxvk_d9vk(): make dll overrides parameter (4) more
   explicit (with checks)
 * link the recommended Wine and Vulkan versions, to the Vulkan
   headers pulled in by both dxvk and vanilla Wine
 * fix dxvk initial release year (2017 vs 2018)
 * fix dxvk versioning: add a leading zero to all dxvk verbs,
   pre-1.0 release
 * add compatibility shim calls, for all version-revised dxvk verbs
 * remove all (inconsistent) use of separators, between dxvk verbs

Winetricks/winetricks,Winetricks/winetricks