re-express the cudax::__tupl::__apply member to make nvc++ happy

[ericniebler]

Description

In #1488, @miscco wants to add the nvhpc compiler to the test matrix, truly a noble ambition. he is blocked by a bit of metaprogramming in cudax that is causing nvc++ to choke. this pr simplifies the code so that nvc++ accepts it.

Checklist

• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[github-actions]

🟩 CI finished in 51m 46s: Pass: 100%/52 | Total: 2h 57m | Avg: 3m 25s | Max: 12m 59s | Hits: 16%/216

• 🟩 cudax: Pass: 100%/52 | Total: 2h 57m | Avg: 3m 25s | Max: 12m 59s | Hits: 16%/216

  🟩 cpu
    🟩 amd64              Pass: 100%/48  | Total:  2h 48m | Avg:  3m 30s | Max: 12m 59s | Hits:  16%/216   
    🟩 arm64              Pass: 100%/4   | Total:  9m 41s | Avg:  2m 25s | Max:  2m 32s
  🟩 ctk
    🟩 12.0               Pass: 100%/19  | Total:  1h 06m | Avg:  3m 30s | Max: 12m 59s | Hits:  16%/108   
    🟩 12.6               Pass: 100%/33  | Total:  1h 51m | Avg:  3m 22s | Max: 11m 55s | Hits:  16%/108   
  🟩 cudacxx
    🟩 nvcc12.0           Pass: 100%/19  | Total:  1h 06m | Avg:  3m 30s | Max: 12m 59s | Hits:  16%/108   
    🟩 nvcc12.6           Pass: 100%/33  | Total:  1h 51m | Avg:  3m 22s | Max: 11m 55s | Hits:  16%/108   
  🟩 cudacxx_family
    🟩 nvcc               Pass: 100%/52  | Total:  2h 57m | Avg:  3m 25s | Max: 12m 59s | Hits:  16%/216   
  🟩 cxx
    🟩 Clang9             Pass: 100%/2   | Total:  5m 57s | Avg:  2m 58s | Max:  3m 08s
    🟩 Clang10            Pass: 100%/2   | Total:  6m 24s | Avg:  3m 12s | Max:  3m 29s
    🟩 Clang11            Pass: 100%/4   | Total: 11m 58s | Avg:  2m 59s | Max:  3m 28s
    🟩 Clang12            Pass: 100%/4   | Total: 12m 01s | Avg:  3m 00s | Max:  3m 14s
    🟩 Clang13            Pass: 100%/4   | Total: 12m 21s | Avg:  3m 05s | Max:  3m 11s
    🟩 Clang14            Pass: 100%/4   | Total: 14m 31s | Avg:  3m 37s | Max:  5m 16s
    🟩 Clang15            Pass: 100%/2   | Total:  5m 45s | Avg:  2m 52s | Max:  2m 56s
    🟩 Clang16            Pass: 100%/4   | Total: 11m 00s | Avg:  2m 45s | Max:  3m 07s
    🟩 Clang17            Pass: 100%/2   | Total:  6m 22s | Avg:  3m 11s | Max:  3m 29s
    🟩 Clang18            Pass: 100%/2   | Total:  7m 45s | Avg:  3m 52s | Max:  4m 49s
    🟩 GCC9               Pass: 100%/2   | Total:  5m 37s | Avg:  2m 48s | Max:  2m 50s
    🟩 GCC10              Pass: 100%/4   | Total: 11m 37s | Avg:  2m 54s | Max:  3m 04s
    🟩 GCC11              Pass: 100%/4   | Total: 11m 28s | Avg:  2m 52s | Max:  2m 54s
    🟩 GCC12              Pass: 100%/7   | Total: 23m 05s | Avg:  3m 17s | Max:  4m 38s
    🟩 GCC13              Pass: 100%/3   | Total:  7m 12s | Avg:  2m 24s | Max:  2m 27s
    🟩 MSVC14.36          Pass: 100%/1   | Total: 12m 59s | Avg: 12m 59s | Max: 12m 59s | Hits:  16%/108   
    🟩 MSVC14.39          Pass: 100%/1   | Total: 11m 55s | Avg: 11m 55s | Max: 11m 55s | Hits:  16%/108   
  🟩 cxx_family
    🟩 Clang              Pass: 100%/30  | Total:  1h 34m | Avg:  3m 08s | Max:  5m 16s
    🟩 GCC                Pass: 100%/20  | Total: 58m 59s | Avg:  2m 56s | Max:  4m 38s
    🟩 MSVC               Pass: 100%/2   | Total: 24m 54s | Avg: 12m 27s | Max: 12m 59s | Hits:  16%/216   
  🟩 gpu
    🟩 v100               Pass: 100%/52  | Total:  2h 57m | Avg:  3m 25s | Max: 12m 59s | Hits:  16%/216   
  🟩 jobs
    🟩 Build              Pass: 100%/47  | Total:  2h 35m | Avg:  3m 18s | Max: 12m 59s | Hits:  16%/216   
    🟩 Test               Pass: 100%/5   | Total: 22m 10s | Avg:  4m 26s | Max:  5m 16s
  🟩 sm
    🟩 90                 Pass: 100%/1   | Total:  2m 21s | Avg:  2m 21s | Max:  2m 21s
    🟩 90a                Pass: 100%/1   | Total:  2m 26s | Avg:  2m 26s | Max:  2m 26s
  🟩 std
    🟩 17                 Pass: 100%/28  | Total:  1h 23m | Avg:  2m 58s | Max:  4m 38s
    🟩 20                 Pass: 100%/24  | Total:  1h 34m | Avg:  3m 56s | Max: 12m 59s | Hits:  16%/216   
  

👃 Inspect Changes

Modifications in project?

	Project
	CCCL Infrastructure
	libcu++
	CUB
	Thrust
+/-	CUDA Experimental
	pycuda
	CUDA C Core Library

Modifications in project or dependencies?

	Project
	CCCL Infrastructure
	libcu++
	CUB
	Thrust
+/-	CUDA Experimental
	pycuda
	CUDA C Core Library

🏃‍ Runner counts (total jobs: 52)

#	Runner
41	linux-amd64-cpu16
5	linux-amd64-gpu-v100-latest-1
4	linux-arm64-cpu16
2	windows-amd64-cpu16