[xpu/triton] Add trtion dequantization kernel

This PR adds xpu backend and trtion kernel for dequantization nf4 dtype.
Tests:
	tests/test_functional.py::TestQuantize4BitFunctional supported nf4 cases
	tests/test_functional.py::Test8BitBlockwiseQuantizeFunctional
implemented quantize_blockwise with binary search that works faster for XPU

Signed-off-by: Dmitrii Makarenko <dmitrii.makarenko@intel.com>

Author: Devjiu

bitsandbytes/__init__.py

@@ -34,6 +34,9 @@
 if torch.cuda.is_available():
     from .backends.cuda import ops as cuda_ops
 
+if torch.xpu.is_available():
+    from .backends.xpu import ops as xpu_ops
+
 
 def _import_backends():
     """