[EPIC] Docs Overhaul

# Summary

[Thrust](https://nvidia.github.io/thrust/), [CUB](https://nvlabs.github.io/cub/), [libcu++](https://nvidia.github.io/libcudacxx/) docs are currently all located at independent URLs as well as use inconsistent style/themes.

# Intended Outcome

As part of the unification of Thrust/CUB/libcu++, we should also unify their docs under a common page for all CCCL docs with a common look and feel. Furthermore, we should use the same style as the new [CUDA Programming Guide](https://docs.nvidia.com/cuda/cuda-c-programming-guide/) with the goal of eventually better integrating CCCL docs into the programming guide.

# 2.2 Tasks
- [ ] https://github.com/NVIDIA/cccl/issues/60
### 2.3 Tasks
- [ ] https://github.com/NVIDIA/cccl/issues/66

### MVP
- [ ] https://github.com/NVIDIA/cccl/issues/642

# Future Tasks
- [ ] https://github.com/NVIDIA/cccl/issues/315
- [ ] https://github.com/NVIDIA/cccl/issues/317
- [ ] https://github.com/NVIDIA/cccl/issues/1128
- [ ] https://github.com/NVIDIA/cccl/issues/53
- [ ] Extract inline code samples to independently compiled files and inline with rst literalinclude
- [ ] Publish overhauled docs in CUDA Programming Guide
- [ ] https://github.com/NVIDIA/cccl/issues/2327
- [ ] https://github.com/NVIDIA/cccl/issues/2841

# Thrust
- [ ] Add documentation for `thrust::cuda::par.on()` https://github.com/NVIDIA/thrust/issues/1013#issuecomment-1443621452
- [ ] https://github.com/NVIDIA/cccl/issues/816
- [ ] https://github.com/NVIDIA/cccl/issues/812
- [ ] https://github.com/NVIDIA/cccl/issues/2321

# CUB
- [ ] https://github.com/NVIDIA/cccl/issues/8790
- [ ] https://github.com/NVIDIA/cccl/issues/8791
- [ ] https://github.com/NVIDIA/cccl/issues/1122
- [ ] https://github.com/NVIDIA/cccl/issues/547
- [ ] https://github.com/NVIDIA/cccl/issues/890
- [ ] https://github.com/NVIDIA/cccl/issues/887
- [ ] https://github.com/NVIDIA/cccl/issues/2319
- [ ] https://github.com/NVIDIA/cccl/issues/2321
- [ ] https://github.com/NVIDIA/cccl/issues/2339
- [ ] https://github.com/NVIDIA/cccl/issues/8997

# Related Info

[How to redirect a GitHub pages URL](https://gist.github.com/domenic/1f286d415559b56d725bee51a62c24a7) for https://nvlabs.github.io/cub