Contribution to fix gh 1887

[oleksandr-pavlyk]

This PR contributes to gh-1890, by streamlining code for performing copy to contiguous array.

1. Save common subexpressions to variables

2. Sub-group size type changed to uint16 (from uint32)

3. sg.get_local_range() replaced with sg.get_max_local_range()

   This is safe to do since work-group size is chosen to be
   a multiple of sub-group size for all possile choices
   of sub-group size (1, 8, 16, 32, 64)

4. Simplified computation of base value in generic branch for
   complex types, or when sg_load is disabled, to avoid a
   division (and left a comment)

---

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/1891/index.html

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310hdf72452_201 ran successfully.
Passed: 895
Failed: 0
Skipped: 119

[ndgrigorian]

LGTM!

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310hdf72452_202 ran successfully.
Passed: 894
Failed: 1
Skipped: 119