Fix failure of proj to JIT-compile associated kernel on HW without fp64-support

[oleksandr-pavlyk]

Closes gh-1275

This PR modifies the kernel associated with dpctl.tensor.proj to avoid using literal constants of type double to allow compilation for hardware without fp64 support.

Modified test test_complex.py::test_complex_output to pass on such HW as well.

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/1276/index.html

[coveralls]

coverage: 83.273%. remained the same when pulling 4dfa3ac on fix-proj into 5ebd6c3 on master.

[github-actions]

Array API standard conformance tests for dpctl=0.14.5dev1=py310h7bf5fec_3 ran successfully.
Passed: 449
Failed: 551
Skipped: 119

[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=0.14.5dev1=py310h7bf5fec_5 ran successfully.
Passed: 447
Failed: 553
Skipped: 119