Pass GLOBAL_TARGETS to rapids_cpm_find() in rapids_cpm_bs_thread_pool()

[KyleFromNVIDIA]

Because the GLOBAL_TARGETS option was not being passed, rapids_cpm_bs_thread_pool() was accidentally calling CPMAddPackage() twice for bs_thread_pool, resulting in invalid pinned versions output. Pass GLOBAL_TARGETS to ensure CPMAddPackage() is only called once.

Description

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• The cmake-format.json is up to date with these changes.
• I have added new files under rapids-cmake/
  • I have added include guards (include_guard(GLOBAL))
  • I have added the associated docs/ rst file and update the api.rst

[robertmaynard]

/merge