Added license headers for pre-unlink/post-link scripts

[oleksandr-pavlyk]

Added license headers for pre-unlink/post-link scripts.

These shell scripts are included in the shipped conda package, and require a license header.

This change is to be backported to maintenance/0.17.x once merged to the development branch.

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[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=0.18.0dev0=py310h15de555_21 ran successfully.
Passed: 890
Failed: 15
Skipped: 91

[coveralls]

coverage: 87.915%. remained the same
when pulling 965b9c7 on add-license-to-dpctl-installation-scripts
into 4a06eb1 on master.

[AndresGuzman-Ballen]

Looks good to me! Thanks!!!