VK_KHR_spirv_1_4 enables SPIR-V 1.4 modules

VK_KHR_spirv_1_4 enables SPIR-V 1.4 modules

In Vulkan 1.1, VK_KHR_spirv_1_4 enables SPIR-V 1.4 modules for assembly
and validation.  This is true even if the underlying Vulkan version doesn't
natively support SPIR-V 1.4.

Deprecates vk::getMaxSpirvVersionForGlsl and vk::getMaxSpirvVersionForAsm
in favour of unified vk::getMaxSpirvVersionForVulkan.

Components: Vulkan

VK-GL-CTS issue: 1712, 1711

Change-Id: I850ab4ec3a0d88485e838d4263d751b2d6e18c08
(cherry picked from commit a7db98c20a6dd4e2366e4fc3ddd368a1fa08b98e)
(cherry picked from commit 0d79d48c0d39989393062af77b475771bba97f80)