Add Python scalar support to `dpt.where`

[ndgrigorian]

This PR proposes a change to dpt.where to add support for Python scalars, aligning it with clip and elementwise functions.

As has been pointed out by the array API community, an common use-case for dpt.where is supporting Python scalars. If the decision to permit them in other elementwise functions is made, where will likely follow suit.

Regardless of the outcome of this decision, it's sensible to support them here.

As the first argument (condition) does not participate in the type promotion in where, if both arguments are scalars, the scalars are treated as the default types for the respective kind.

• [X] Have you provided a meaningful PR description?
• [X] Have you added a test, reproducer or referred to an issue with a reproducer?
• [X] Have you tested your changes locally for CPU and GPU devices?
• [X] Have you made sure that new changes do not introduce compiler warnings?
• [ ] Have you checked performance impact of proposed changes?
• [ ] If this PR is a work in progress, are you opening the PR as a draft?

[github-actions[bot]]

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

[github-actions[bot]]

Array API standard conformance tests for dpctl=0.18.0dev0=py310h15de555_80 ran successfully. Passed: 894 Failed: 15 Skipped: 105

[coveralls]

coverage: 87.965% (-0.09%) from 88.057% when pulling 20929bec233d2525701234f2e9610ac36a44a161 on support-scalars-in-where into 26d34f565d36572b3207cd1e969312eae4eabacc on master.

[github-actions[bot]]

Array API standard conformance tests for dpctl=0.18.0dev0=py310h15de555_81 ran successfully. Passed: 894 Failed: 15 Skipped: 105

[coveralls]

coverage: 87.965% (-0.09%) from 88.057% when pulling 9f449d1f1f03ae0a447f2575b1626821716717b9 on support-scalars-in-where into 26d34f565d36572b3207cd1e969312eae4eabacc on master.

[ndgrigorian]

CI failure is unrelated to this PR, I will go ahead and merge it