Add UCXX and NCCL to libraft conda recipe

[divyegala]

libraft recipe installs the distributed component

raft/conda/recipes/libraft/recipe.yaml

Line 94 in 902ed56

cmake --install cpp/build --component distributed

which has a build and runtime dependency on targets from NCCL and ucxx as seen here

raft/cpp/CMakeLists.txt

Lines 392 to 406 in 902ed56

	rapids_export_package(
	BUILD ucxx raft-distributed-exports COMPONENTS ucxx python GLOBAL_TARGETS ucxx::ucxx ucxx::python
	)
	rapids_export_package(
	INSTALL ucxx raft-distributed-exports COMPONENTS ucxx python GLOBAL_TARGETS ucxx::ucxx
	ucxx::python
	)
	rapids_export_package(BUILD NCCL raft-distributed-exports)
	rapids_export_package(INSTALL NCCL raft-distributed-exports)
	# ucx is a requirement for raft_distributed, but its config is not safe to be found multiple times,
	# so rather than exporting a package dependency on it above we rely on consumers to find it
	# themselves. Once https://github.com/rapidsai/ucxx/issues/173 is resolved we can export it above
	# again.
	target_link_libraries(raft_distributed INTERFACE ucx::ucp ucxx::ucxx NCCL::NCCL)

cc @gforsyth @bdice

[gforsyth]

The changes look good overall @divyegala -- there are a few additional changes we need to make to avoid overconstraining outputs, and then some small style changes.

Anything in the cache host dependencies that has a run export is inherited by all the outputs.

Can you add nccl to the ignore_run_exports for the libraft-tests, libraft, and libraft-static outputs?

[divyegala]

@gforsyth thanks for your review! I incorporated your change requests. Let me know what else this PR needs.

[gforsyth]

Looks good to go if CI is green!

[divyegala]

/merge