Build/CI: Bring back (C) header checks #1633
Description
Describe the bug
#1562 removed the check for and automatic application of (C) headers.
It's too easy to have the wrong (C) header in files. Checks in CI and automatic application help a lot.
Spotless offers ways for what's mentioned on #1562 - for example targetExcludeIfContentContains/Regex.
To Reproduce
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Actual Behavior
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Expected Behavior
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Additional context
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System information
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