Move official examples dedicated to one engine directly in the engine repo

Some official example are still in this repository even after https://github.com/eclipse/gemoc-studio-modeldebugging/pull/147

Keeping example in the main repo would make sense only if the example involves several engines. For example one main base dsl reused by melange to produce several dsl working with different metaprog approaches.

Currently, none of the example in the folder /official_example has been built with this goal in mind, so they should move to their target engine repository ( K3FSM and MelangeK3FSM -> gemoc-studio-execution-java) (in addition to the dedicated example deployer plugin)

content of /official_samples/FSMModelAdaptation/language_workbench seems to be deprecated and need to be removed