request #7342 Tv3 export to Tv5: migration abort when files are deleted on file system

As we are running in a single process, there is no need to export to zip archive
we can just refer to files where they are on file system

Change-Id: I57c7f18e8561d202b02d850980571a88177eab9e
Merge commit 'refs/changes/88/2888/6' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  request #7342 Tv3 export to Tv5: migration abort when files are deleted on file system

Change-Id: Ia88adb843f2bc3e8ebb8c1717941527e1be73cbf
This is Tuleap 7.3.99.63

Change-Id: I79db51cde50d0ca82ba003d2ec47279b3cd7e55e