Update license headers for 18

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apps/admin_audit/lib/Actions/Sharing.php

apps/comments/lib/Search/Result.php

apps/dav/appinfo/v1/publicwebdav.php

apps/dav/appinfo/v1/webdav.php

apps/dav/lib/Connector/PublicAuth.php

apps/dav/lib/Connector/Sabre/ServerFactory.php

...ests/unit/Connector/Sabre/RequestTest/RequestTestCase.php

apps/federatedfilesharing/appinfo/app.php

apps/federatedfilesharing/lib/AppInfo/Application.php

apps/federatedfilesharing/lib/FederatedShareProvider.php

...ratedfilesharing/lib/ocm/CloudFederationProviderFiles.php

apps/files/lib/AppInfo/Application.php

apps/files/lib/BackgroundJob/ScanFiles.php

apps/files/lib/Command/Scan.php

apps/files/lib/Command/ScanAppData.php

apps/files/lib/Db/TransferOwnershipMapper.php

...files/lib/Listener/LegacyLoadAdditionalScriptsAdapter.php

apps/files/lib/Migration/Version11301Date20191205150729.php