Fix Coverity parse error in AlgTool.h.
In AlgTool.h, we had
Gaudi::Property<int> m_outputLevel{this, "OutputLevel", setUpMessaging(),
[this]( auto& ) { this->updateMsgStreamOutputLevel( this->m_outputLevel ); },
"output level"};
Coverity, however, does not correctly resolve the auto here and reports a parse error, which cascades downwards to many other loci. Resolve by writing the type explicitly; that seems to make Coverity happy.