* Add Gtest version 1.13.0 and 1.14.0 , And modify the standard to c++14
* Update xmake.lua
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Co-authored-by: Jérôme Leclercq <lynix680@gmail.com>
Configuration options have been added to decide whether or not `gtest_main` should be linked against.
For consistency, a similar option was added for the `gmock` target.