Fix dpctl.tensor.isdtype function signature

[ndgrigorian]

This pull request moves isdtype to _type_utils.py to make the function signature match what is required by the array API specification.

Additionally experiments with using the --disable-deadline when running array API tests, as some tests fail for exceeding the deadline.

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/1501/index.html

[github-actions]

Array API standard conformance tests for dpctl=0.15.1dev3=py310h15de555_20 ran successfully.
Passed: 907
Failed: 2
Skipped: 86

[coveralls]

coverage: 90.684%. remained the same
when pulling 7a1bef7 on aa-conformity-chores
into 3277028 on master.

[github-actions]

Array API standard conformance tests for dpctl=0.15.1dev3=py310h15de555_23 ran successfully.
Passed: 909
Failed: 0
Skipped: 86

[oleksandr-pavlyk]

Thank you @ndgrigorian