CMakeProjectManager: Add package manager auto-setup

Adds CMAKE_PROJECT_INCLUDE_BEFORE as initial CMake parameters
with a path to a auto-setup.cmake script that will run
conan install if a conanfile.txt is found in the prject.

A project can have a local QtCreatorPackageManager.cmake file
that will be loaded if exists.

The auto setup can be controlled via the following CMake variables:

* QT_CREATOR_SKIP_PACKAGE_MANAGER_SETUP
* QT_CREATOR_SKIP_CONAN_SETUP
* QT_CREATOR_SKIP_VCPKG_SETUP

conan.cmake is taken from https://github.com/conan-io/cmake-conan
which takes care of the conan specific compiler cruft. License
is MIT.

Fixes: QTCREATORBUG-25362
Change-Id: I70a6e1abc5600851d048f1590ca24204ce52a503
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.cpp

@@ -31,6 +31,8 @@
 #include "cmakeconfigitem.h"
 #include "cmakekitinformation.h"
 #include "cmakeprojectconstants.h"
+#include "cmakeprojectplugin.h"
+#include "cmakespecificsettings.h"
 #include "configmodel.h"
 #include "configmodelitemdelegate.h"
 
@@ -674,6 +676,14 @@ static QStringList defaultInitialCMakeArguments(const Kit *k, const QString buil
         initialArgs.append(QString::fromLatin1("-DCMAKE_BUILD_TYPE:String=%1").arg(buildType));
     }
 
+    Internal::CMakeSpecificSettings *settings
+        = Internal::CMakeProjectPlugin::projectTypeSpecificSettings();
+
+    // Package manager
+    if (settings->packageManagerAutoSetup())
+        initialArgs.append(QString::fromLatin1("-DCMAKE_PROJECT_INCLUDE_BEFORE:PATH=%1")
+                           .arg("%{IDE:ResourcePath}/package-manager/auto-setup.cmake"));
+
     // Cross-compilation settings:
     if (!isIos(k)) { // iOS handles this differently
         const QString sysRoot = SysRootKitAspect::sysRoot(k).toString();