CMake: update output name summary (useful for Windows builds)

[jmckenna]

• enhances the recent PR
• to also output the variable PROJ_OUTPUT_NAME in the CMake summary
  • otherwise, CMake tries to use the old PROJ_CORE_TARGET_OUTPUT_NAME variable, which no longer exists, resulting in the new name not showing in the CMake summary, such as:

        -- PROJ_CORE_TARGET_OUTPUT_NAME  =
        -- BUILD_SHARED_LIBS             = ON
        -- PROJ_LIBRARIES                = proj