Move kernels to their own namespaces to avoid build conflicts #810

Job	Run time
Compute matrix	2s
Doxygen check	13s
Verify Dev Containers / Verify devcontainers	17s
CUDA12.6 gcc / arm64 / Build gcc12/C++17 / Build gcc12/C++17	4m 33s
CUDA12.6 gcc / amd64 / Build gcc13/C++17 / Build gcc13/C++17	5m 3s
CUDA11.8 gcc / amd64 / Build gcc11/C++17 / Build gcc11/C++17	5m 13s
CUDA12.6 gcc / amd64 / Build gcc12/C++17 / Build gcc12/C++17	4m 33s
Verify Dev Containers / List devcontainers	4s
Verify Dev Containers / cuda12.6-gcc13	1m 16s
Verify Dev Containers / cuda12.6-gcc13	1m 5s
Verify Dev Containers / cuda12.6-gcc12	59s
Verify Dev Containers / cuda11.8-gcc11	1m 1s
CUDA12.6 gcc / arm64 / Test ${{ inputs.test_name }}	0s
CUDA12.6 gcc / amd64 / Test gcc12/C++17 / Test gcc12/C++17	6m 25s
CUDA12.6 gcc / amd64 / Test ${{ inputs.test_name }}	0s
CUDA11.8 gcc / amd64 / Test gcc11/C++17 / Test gcc11/C++17	5m 39s
CI success	1s
	36m 24s

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