ProjectExplorer: Let RunConfiguration declare what nodes it belongs to

This feature in question is the availability of the "Run" button in the
context menu of certain project nodes in the project tree to run
something presumably related to/build from that (sub)project.

Previously, the decision was made for certain qmake based projects
(those targeting Desktop, iOS and VxWorks) by some indirection
through the corresponding RunConfigurationFactories.

The patch lets the RunConfigurations decide themselves directly
and removes the indirection, potentially opening the feature for
other qmake based RCs, as well as other combinations (e.g.
PythonRunConfiguration could be associated with its .py file,
without the need to have a dummy project)

Change-Id: Ic489bd1dfa25fcd9102ffa4fa30125565dd2e40e
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/ios/iosrunconfiguration.cpp

@@ -157,6 +157,11 @@ void IosRunConfiguration::updateEnabledState()
     return RunConfiguration::updateEnabledState();
 }
 
+bool IosRunConfiguration::canRunForNode(const Node *node) const
+{
+    return node->filePath() == m_profilePath;
+}
+
 IosDeployStep *IosRunConfiguration::deployStep() const
 {
     DeployConfiguration *config = target()->activeDeployConfiguration();