Check latest version of gtest suite

At the moment we are using a very old version of gtest in our unit-tests (v1.6.0, from year 2011), while the latest version is v1.12.0 (from 2022).

Therefore, we should find a way to move to a more recent version.

Newer versions are available to us in LCG releases repo: link1, link2

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A possible approach is to repackage v1.12.0 for internal use.