Use error_handler if getSymbol encountered error and returns nullptr

[oleksandr-pavlyk]

This PR adds call to error_handler into the branch of DynamicLibHelper::getSymbol where it returns nullptr because of an error,

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/956/index.html

[coveralls]

Coverage decreased (-0.02%) to 82.033% when pulling f24aa12 on use-error-handle-in-getSymbol into 36c8f71 on master.

[github-actions]

Array API standard conformance tests for dpctl=0.14.0dev0=py310h8c27c75_228 ran successfully.
Passed: 33
Failed: 801
Skipped: 3138

[github-actions]

Array API standard conformance tests for dpctl=0.14.0dev0=py310h8c27c75_228 ran successfully.
Passed: 33
Failed: 801
Skipped: 3138

[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=0.14.0dev0=py310h8c27c75_230 ran successfully.
Passed: 33
Failed: 801
Skipped: 3138