[TASK] Move language include to .xlf

Move all old language includes (php,xml) in the core to .xlf

Change-Id: I804b5970a360cbfdc2940736632c55c535ccbd40
Resolves: #49832
Releases: 6.2
Reviewed-on: https://review.typo3.org/22167
Reviewed-by: Markus Klein
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer