[GPU/WGF] Use ByteAddressBuffer in precompiled shaders

Drivers and hardware may provide more optimal paths for untyped buffers
compared to typed.

Also, ByteAddressBuffer may be bound via a root descriptor in Direct3D 12,
greatly simplifying the binding logic.

ByteAddressBuffer also doesn't have the 128 * 2^20 element count limit that
typed and structured buffers have, and doesn't require the structure stride
to be specified at resource creation time in Direct3D 11.

src/xenia/gpu/texture_cache.h

@@ -426,11 +426,6 @@ class TextureCache {
   };
 
   struct LoadShaderInfo {
-    // Log2 of the sizes, in bytes, of the elements in the source (guest) and
-    // the destination (host) buffer bindings accessed by the copying shader,
-    // since the shader may copy multiple blocks per one invocation.
-    uint32_t source_bpe_log2;
-    uint32_t dest_bpe_log2;
     // Number of bytes in a host resolution-scaled block (corresponding to a
     // guest block if not decompressing, or a host texel if decompressing)
     // written by the shader.