CMakePM: Add ability to stop CMake run in Settings

Previously the only way to stop the CMake run was to click on "x"
button of the "Configure" progress bar.

Now you can click in Settings on "Stop CMake".

Change-Id: I167b86ba62679f197c194148b122ff0c87e87162
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/cmakeprojectmanager/cmakeprocess.h

@@ -51,6 +51,7 @@ public:
     ~CMakeProcess();
 
     void run(const BuildDirParameters &parameters, const QStringList &arguments);
+    void terminate();
 
     QProcess::ProcessState state() const;