Texture should support integer formats.

**Is your feature request related to a problem? Please describe.**
I have an 8-bit integer array and I want to set it as the texture. However, I have to convert it to float format first, which is a great overhead.

**Describe the solution you'd like**
Add integer support for raw textures.

**Describe alternatives you've considered**
Add integer array versions of `LoadTextureFromArrayRaw`, and add additional supports above it.