Texture Cache: Add HLE methods for building 3D textures within the GPU in certain scenarios.

This commit adds a series of HLE methods for handling 3D textures in
general. This helps games that generate 3D textures on every frame and
may reduce loading times for certain games.

src/video_core/textures/decoders.h

@@ -12,6 +12,10 @@ namespace Tegra::Texture {
 
 // GOBSize constant. Calculated by 64 bytes in x multiplied by 8 y coords, represents
 // an small rect of (64/bytes_per_pixel)X8.
+inline std::size_t GetGOBSize() {
+    return 512;
+}
+
 inline std::size_t GetGOBSizeShift() {
     return 9;
 }