Make stream a keyword-only argument in usm_ndarray.to_device

[ndgrigorian]

This PR fixes a small nonconformity with the array API by making stream a keyword-only argument

Closes #1965

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[github-actions]

Deleted rendered PR docs from intelpython.github.com/dpctl, latest should be updated shortly. 🤞

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310h93fe807_442 ran successfully.
Passed: 895
Failed: 1
Skipped: 118

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310h93fe807_453 ran successfully.
Passed: 894
Failed: 2
Skipped: 118

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310h93fe807_441 ran successfully.
Passed: 894
Failed: 2
Skipped: 118

[coveralls]

coverage: 87.681%. remained the same
when pulling 19145cf on fix-to-device-kwargs
into 598082f on master.

[antonwolfy]

It seems test coverage for stream keyword is missing.