Tests: merge SofaTests with Sofa.Testing

[hugtalbot]

Further #1834 :

Tests: merge SofaTests with Sofa.Testing
Make sure that examples (see in Plugin Example : https://github.com/sofa-framework/sofa/blob/master/applications/plugins/PluginExample/PluginExample_test/MyBehaviorModel_test.cpp) and doc are up to date: https://www.sofa-framework.org/community/doc/contributing-to-sofa/writing-tests/

Connected to #417 #489

and PRs: #455 #471

[fredroy]

A list of tasks to do:

1. remove SofaTest use in Sofa*_test (first in the most important modules SofaBase* and then SofaCommon and ...)
2. dispatch the existing tests in the SofaTest

I suppose 1) will involve to add/modify the new Sofa.Testing API.
This post will surely be updated heavily soon....

[hugtalbot]

How far are we on this @fredroy? same point?

[hugtalbot]

congrats @fredroy !!!! 👏 👏 👏