Produce the P2 repository with maven repository compatibility.

[ylussaud]

This will ease the consumption of M2Doc binaries for standalone (outside Eclipse) uses.

This can be done with CBI/aggregator.

[ylussaud]

This has been done for Acceleo 4 in that commit. The idea is to build and deploy p2 artifacts and then reuse them in a maven build that create the maven artifacts other maven projects can depend on.

We should probably wait for AQL 8.x dependency so we can depend on the maven artefact from Acceleo 4.