[java] move applicative code in app directory
Revert "[java] move applicative code in app directory"

This reverts commit f3cf8ffb0f5c18911675a8c79b8c9807ffae4640.
[java] Tests can pass on a platform with 'mvn -Dfr.valtech.host=exemple.org:80 clean install -f mepc-functionnal-tests/pom.xml'
[slides] fix typo
[slides] Renumerate steps