Add support foe disabled gtests by flagging them as skipped

[twigs]

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Context

Without this fix disabled gtest test are listed as successful test executions instead of skipped tests.
This is due to the fact that gtests indicates disabled tests by setting status to notrun instead of using a skipped element in the junit output.
[//]: # (
Describe the problem or feature in addition to a link to the issues
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Checklist

• Sign Allure CLA
• Provide unit tests

[baev]

@twigs thanks!