Update dlpack to v1.2

[ndgrigorian]

This PR proposes updating the vendored DLPack header dlpack.h to v1.2 and adds data type code and device type enum definitions where necessary

It does not work towards supporting the new C functions to optimize speed of exchange, which could be done in a follow-up PR

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• Have you made sure that new changes do not introduce compiler warnings?
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[github-actions]

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

[coveralls]

coverage: 86.267% (-0.009%) from 86.276%
when pulling 043481b on update-dlpack-v1.2
into 70920d3 on master.

[github-actions]

Array API standard conformance tests for dpctl=0.22.0dev0=py310h93fe807_26 ran successfully.
Passed: 1110
Failed: 48
Skipped: 82

[github-actions]

Array API standard conformance tests for dpctl=0.22.0dev0=py310h93fe807_51 ran successfully.
Passed: 1110
Failed: 48
Skipped: 82

[antonwolfy]

LGTM! No more comments from me.
Thank you @ndgrigorian