CMake: Include dependency on Threads in published TBBConfig.cmake

[p12tic]

Currently neither TBBConfig.cmake nor TBBTargets.cmake specify dependency on Threads package even though TBBTargets.cmake list Threads::Threads among INTERFACE_LINK_LIBRARIES of TBB::tbb library.

This causes configuration failures in projects that specify dependency on TBB via find_package(TBB), but don't themselves depend on the Threads package.

At the moment there's no other way to fix this except to specify the dependency manually.

Maybe some day this will be handled automatically in CMake. This is the bug that tracks such feature: https://gitlab.kitware.com/cmake/cmake/-/issues/20511.

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• [x] bug fix - change that fixes an issue
• [ ] new feature - change that adds functionality
• [ ] tests - change in tests
• [ ] infrastructure - change in infrastructure and CI
• [ ] documentation - documentation update

Tests

• [ ] added - required for new features and some bug fixes
• [x] not needed

Documentation

• [ ] updated in # - add PR number
• [ ] needs to be updated
• [x] not needed

Breaks backward compatibility

• [ ] Yes
• [x] No
• [ ] Unknown