Allow changing the build directory, and reparse.

Task:  250418

This also moves us closer to supporting multiple build configurations
properly.

src/plugins/cmakeprojectmanager/cmakerunconfiguration.cpp

@@ -81,7 +81,7 @@ QStringList CMakeRunConfiguration::commandLineArguments() const
 
 ProjectExplorer::Environment CMakeRunConfiguration::environment() const
 {
-    // TODO
+    // TODO have a way for the user to setup the environment
     return ProjectExplorer::Environment::systemEnvironment();
 }