use inline code formatting in docs for variables, functions, and modules

[jameslamb]

Description

Reading through the docs today, I found a few places where it looked like italics were being used when inline code formatting would be clearer.

I expected that in many of these cases, inline code formatting was actually intended, but just mistakenly not applied. When you're mostly writing markdown, it's easy to get in the habit of using a single backtick for inline code formatting... reStructuredText uses 2 backticks.

For example, at https://docs.rapids.ai/api/rapids-cmake/stable/packages/rapids_cpm_versions/.

This proposes changing them to inline code formatting, to make the names of things like environment variables more obvious visually.

Notes for Reviewers

After noticing a few in the rendered docs, I looked for other possible cases like this.

git grep -E ' \`[^\`]+' *.rst

Used my best judgment to decide which seemed like they should be inline code formatting.

Checklist

• [x] I am familiar with the Contributing Guidelines.
• [ ] New or existing tests cover these changes.
• [x] The documentation is up to date with these changes.
• [x] The cmake-format.json is up to date with these changes.
• [ ] I have added new files under rapids-cmake/
  • [ ] I have added include guards (include_guard(GLOBAL))
  • [ ] I have added the associated docs/ rst file and update the api.rst

[robertmaynard]

/merge