Rework CMake dependencies management (Fix #1116)

- By default don't build dependencies simply call find_package()
- By default only build C++ library
- IF building Python, Java or .Net wrapper then force build dependencies
  - Build dependencies as STATIC
  - Build and Install (in CMAKE_BINARY_DIR) dependencies at configure time

cmake/java.cmake

@@ -9,3 +9,7 @@ find_package(JNI REQUIRED)
 if(NOT TARGET ortools::ortools)
   message(FATAL_ERROR "Java: missing ortools TARGET")
 endif()
+
+if(BUILD_TESTING)
+  add_subdirectory(examples/java)
+endif()