Merge uv Python documentation.

[TRLarsen]

This PR updates the documentation to include:

• a section in the CMake page on installing newer versions of CMake on externally managed (lab) computers using either uv or pipx.
• a section in the Python Environments page on using uv to manage python environments/dependencies.

[TRLarsen]

I've built and examined the content locally to ensure it renders correctly.