Use specilized kernel for f-arrays and sum by axis=1. Add keepdims support

Author: AlexanderKalistratov

dpnp/dpnp_iface_mathematical.py

@@ -1828,12 +1828,18 @@ def sum(
     elif where is not True:
         pass
     else:
-        if axis == (0,) and len(x.shape) == 2 and not keepdims:
+        if len(x.shape) == 2 and (
+            (axis == (0,) and x.flags.c_contiguous)
+            or (axis == (1,) and x.flags.f_contiguous)
+        ):
             from dpctl.tensor._reduction import _default_reduction_dtype
 
             from dpnp.backend.extensions.sycl_ext import _sycl_ext_impl
 
-            input = dpnp.get_usm_ndarray(x)
+            input = x
+            if axis == (1,):
+                input = input.T
+            input = dpnp.get_usm_ndarray(input)
 
             queue = input.sycl_queue
             out_dtype = (
@@ -1850,7 +1856,14 @@ def sum(
 
             if sum:
                 sum(input, output, []).wait()
-                return dpnp_array._create_from_usm_ndarray(output)
+                result = dpnp_array._create_from_usm_ndarray(output)
+
+                if keepdims:
+                    result = result.reshape((1,) + output.shape)
+                    if axis == (1,):
+                        result = result.T
+
+                return result
 
         y = dpt.sum(
             dpnp.get_usm_ndarray(x), axis=axis, dtype=dtype, keepdims=keepdims