Implemented support for constructing MemoryUSM* from object with __sycl_usm_array_interface__ when array-info is not contiguous

[oleksandr-pavlyk]

Closes #396

This PR permits constructor calls like dpctl.memory.MemoryUSMShared( obj_with_suai ) to work with Python object whose __sycl_usm_array_interface__ dictionary specifies non-contiguous strides, and non-byte-size type-string, used to address elements of a contiguous block of memory.

I.e. index tuple (i0, i1, ...) would address element offset + strides[0]*i0 + strides[1]*i1 + ... in C-array of dimension shape[0]*shape[1]*....

In this case type-less USM memory buffer created addresses memory from the minimal index to maxima index (inclusive) generated by enumeration of all displacements offset + strides[0]*i0 + strides[1]*i1 + ... when iterating over all possible tuple of indexes in determined by the shape.

Example:

import numpy as np
import dpctl
import dpctl.memory as dpmem

class View:
    def __init__(self, buffer, shape, strides, offset):
        self.buffer=buffer
        self.shape=shape
        self.strides=strides
        self.offset = offset

    @property
    def __sycl_usm_array_interface__(self):
        sua_iface = self.buffer.__sycl_usm_array_interface__
        sua_iface['offset'] = self.offset
        sua_iface['shape'] = self.shape
        sua_iface['strides'] = self.strides
        return sua_iface

# Allocate 32 bytes, and fill them with canary numbers
buf = dpmem.MemoryUSMShared(32)
buf.copy_from_host(np.full((32,), 77, dtype='|u1'))

# View of 10 bytes, starting with byte 8, and going every other byte
v = View(buf, (10,), strides=(2,), offset=8)

# Create USMShared buffer from the view 
# spanning from the lowest byte, offset=8 to highest byte, offset=8 +(10-1)*2
buf2 = dpmem.MemoryUSMShared(v)
# That is total of 19 bytes, (counting the last one too)
assert buf2.nbytes == 19
# populate this buffer with different values
buf2.copy_from_host(np.full((19,), 1, dtype="|u1"))
# copy content of the parent buffer to host
res = buf.copy_to_host()
del buf
del buf2
print(res)

Executing this prints

[77 77 77 77 77 77 77 77  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
  1  1  1 77 77 77 77 77]

[diptorupd]

Please squash and merge.