Support use of external/system GTest installation

[iskunk]

(Re-push of #1384)

I am building the project in a restricted environment that does not allow network access (so FetchContent is not usable), and already have a pre-compiled build of GTest ready to go. With this change, I can pass -DCUTLASS_USE_SYSTEM_GOOGLETEST=ON -DGTest_ROOT=/path/to/gtest-install to CMake, and the tests will build using the specified install. A system install of GTest can also be picked up.

The second commit fixes a related issue: the test suite breaks when the bin/ subdirectory is missing from the build tree, but it's the bundled-googletest logic that creates it. So we create that dir explicitly/unconditionally.

[github-actions[bot]]

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[iskunk]

Is there an additional step needed for merging? Anything I need to do?

[github-actions[bot]]

This PR has been labeled inactive-30d due to no recent activity in the past 30 days. Please close this PR if it is no longer required. Otherwise, please respond with a comment indicating any updates. This PR will be labeled inactive-90d if there is no activity in the next 60 days.

[iskunk]

What is the status of development on this project? It does not appear to have received a commit, from anyone, for nearly a month.

[thakkarV]

@d-k-b can you please shepherd this MR? I see that you have approved it. CC: @hwu36

@iskunk we are about to release 3.5.1 and due to logistics of our release process, we will likely only merge this after 3.5.1 is pushed out next week. Is that ok? Sorry for the delay.

[d-k-b]

@hwu36 to confirm, but I believe this fix will come with 3.5.1. If not, we can certainly merge it shortly after.

[iskunk]

@thakkarV: After 3.5.1 is fine; just want to make sure this gets in.