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>

doc/qtcreator/src/overview/creator-acknowledgements.qdoc

@@ -1003,5 +1003,40 @@
         FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
         OTHER DEALINGS IN THE FONT SOFTWARE.
         \endcode
+
+        \li \b conan.cmake
+
+        CMake script used by Qt Creator's auto setup of package manager dependencies.
+
+        The sources can be found in:
+        \list
+            \li \c QtCreator/src/share/3rdparty/package-manager/conan.cmake
+            \li \l https://github.com/conan-io/cmake-conan
+        \endlist
+
+        The MIT License (MIT)
+
+        Copyright (c) 2018 JFrog
+
+        \badcode
+        Permission is hereby granted, free of charge, to any person obtaining a copy
+        of this software and associated documentation files (the "Software"), to deal
+        in the Software without restriction, including without limitation the rights
+        to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+        copies of the Software, and to permit persons to whom the Software is
+        furnished to do so, subject to the following conditions:
+
+        The above copyright notice and this permission notice shall be included in all
+        copies or substantial portions of the Software.
+
+        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+        FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+        AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+        LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+        OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+        SOFTWARE.
+        \endcode
+
      \endlist
 */