Fix the handle of not applicable NetworkModification when throwException boolean is present

[alicecaron]

In the NetworkModification::apply methods that take the throwException boolean in input parameter the use of AbstractNetworkModification::logOrThrow method should be called when the network modification cannot be applied.

This method allows to either log the not applicable reason as a warning (if throwException=false) or to throw a PowsyblException (if throwException=true).

Problem:
Some of the NetworkModification::apply method implementations do not call this method when the modification can not be applied.

Solution:
Fix each of thoses implementations to use the logOrThrow method.

Example:
In ConnectGenerator::apply we throw a PowsyblException in some case, but we should logOrThrow instead (and in case it is a log we should then return):

Replace

throw new PowsyblException("Generator '" + generatorId + "' not found");

With

logOrThrow(throwException, "Generator '" + generatorId + "' not found");
return;