Move usm_ndarray API class into dpctl/tensor

[vlad-perevezentsev]

This PR moves usm_ndarray class along with related cython and python internals and utilities into dpctl/tensor without enabling build or test coverage at this stage

The migration of dpctl.tensor._tensor_impl will be handled in a follow-up PR

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/pull/2749/index.html

[github-actions]

Array API standard conformance tests for dpnp=0.20.0dev2=py313h509198e_24 ran successfully.
Passed: 1227
Failed: 0
Skipped: 9