[BUGFIX] GeneralUtility->copyDirectory does not fix permissions

Instead of using TYPO3-internal functions
for creating directories and moving files,
default PHP functions are used. This creates
problems with permissions e.g. when
installing the introduction package.

Releases: 6.2
Resolves: #57298
Change-Id: Ifa5e92fd245db033dacbc3bcd15d487bd7af2101
Reviewed-on: https://review.typo3.org/28772
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer
Reviewed-by: Ernesto Baschny
Tested-by: Ernesto Baschny