[Releng] XWT repository architecture update

- migrate to EPL 2.0 for simrel consistency
- convert files to unix encoding to simplify further maintenance
- modified the repository architecture for better visualisation
- uniformized some headers to facilitate automation of modifications

Change-Id: I387c7ccf6fff9ee35075ea4f419fc87a335e44f2
Signed-off-by: Quentin Le Menez <quentin.lemenez@cea.fr>