fix(core): prevent race condition when adding a new id

Description

There is a race condition in fwID::addIDInDictionary() because call fwID::isIdFound() before locking the mutex.

Closes #859 (closed)

How to test it?

Launch coretest. Many many times.

Or, before leaving the office at the end of the day, launch in several terminals:

ctest --repeat until-fail:99999 --output-on-failure --stop-on-failure -j 12 -R coretest