ProjectExplorer: De-QObject-ify BuildConfigurationFactories

The QObject was not heavily used. Object name was for debugging only,
translation context can be taken from the corresponding BuildConfiguration
objects, the qobject_casts in the three big importers are replaced by
dynamic_cast, which is good enough in that context.

Take the opportunity to re-use translations from base BuildConfiguration
for the common cases and sprinkle in some 'final'.

Change-Id: I8e9727c98c6e943cb333556861c24e701c2bdf45
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/nim/project/nimblebuildconfiguration.cpp

@@ -99,8 +99,8 @@ NimbleBuildConfigurationFactory::NimbleBuildConfigurationFactory()
             return info;
         };
         return QList<BuildInfo>{
-            oneBuild(BuildConfiguration::Debug, tr("Debug")),
-            oneBuild(BuildConfiguration::Release, tr("Release"))
+            oneBuild(BuildConfiguration::Debug, BuildConfiguration::tr("Debug")),
+            oneBuild(BuildConfiguration::Release, BuildConfiguration::tr("Release"))
         };
     });
 }