move wheel installs into per-project test scripts, other packaging changes

[jameslamb]

Proposes some changes to small things I noticed while working on #4804.

• CMake option cleanup:
  • adds BUILD_PRIMS_BENCH OFF, removes BUILD_BENCH OFF in get_raft.cmake (matching changes to RAFT from 23.04: Add end-to-end CUDA ann-benchmarks to raft raft#1304)
  • adds BUILD_BENCHMARKS OFF in get_cudf.cmake (this is the default, but better to be explicit)
• consolidates some .gitignore rules, adds wheels and conda packages there
• moves responsibility for installing CI artifacts into ci/test_wheel_{package}.sh and out of ci/test_wheel.sh
• splits up Cython and scikit-build-core in dependencies.yaml
  • every Python package here using Cython also uses scikit-build-core, but the reverse won't be true as of WIP: [DO NOT MERGE] introduce libcugraph wheels #4804 ... making that change here is harmless and reduces the size of the diff in WIP: [DO NOT MERGE] introduce libcugraph wheels #4804 a bit

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[jameslamb]

Since this hasn't been reviewed yet... gonna move it back to draft and cancel CI. There are some more small changes I'd like to include here.

put it back up for review after pushing 6776530

[KyleFromNVIDIA]

Looks good, just one quick request for .gitignore

[jameslamb]

/merge