Add Sphinx docs for `cuda.pathfinder`

[leofang]

btw @rwgk could you create an issue to track the need to add docs for pathfinder? We need a Sphinx-rendered docs.

Originally posted by @leofang in #723 (comment)

[leofang]

We need

1. https://nvidia.github.io/cuda-python/cuda-pathfinder/
2. Add cuda.pathfinder to the landing page https://nvidia.github.io/cuda-python/ and the root README.md

[leofang]

@copilot, please copy/paste the existing Sphinx documentation infrastructure to cuda_pathfinder/docs so that we build a skeleton for Ralf to refine the texts later.

• It is OK to only retain 1.1.0 in nv-versions.json
• There are a few places where we hardcoded the hyperlinks to the pathfinder README. Those should be replaced by the (hardcoded) url to the pathfinder docs.
• When build-docs.yml takes components "all", it needs to update pathfinder docs too