Remove the Quickfix/J forceResync setting and replace it with a ValidateSequenceNumbers setting

The ForceResync option has been introduced by QFJ-427.
After discussion between the developers, it has been agreed to replace it by a new setting ValidateSequenceNumbers defaulting to true.
When the setting ValidateSequenceNumbers is set to false, no check (check too high or check to low) will be done on the incoming seq num (but the store will not be artificially synched to the actual received seq num).