Fix for unnormalized coordinate test using mipmaps

Fix for unnormalized coordinate test using mipmaps

The unnormalized coodinate test used textures with mipmaps, while
unnormalized coordinates are only defined for single mip level textures.
This required adding new constructors to the texture framework that
allow explicit setting of mip levels.

Affects:

dEQP-VK.texture.filtering.unnormal.*

Components: Vulkan, Framework

VK-GL-CTS issue: 1390

Change-Id: Ibd049a04d143979624d10148e3911728579b3a2c