dev: include generated config and function docs in the local lint suite

[kumarUjjawal]

Which issue does this PR close?

• Part of Add Local Scripts to Reproduce Full CI #21048.

Rationale for this change

dev/rust_lint.sh does not check the generated configs.md and function pages. A contributor finds a stale page only in the config-docs-check job. That job also regenerates the tracked pages in place and then runs git diff, so the same check cannot run in a working tree with other changes.

What changes are included in this PR?

• ci/scripts/check_config_function_docs.sh regenerates the four pages into per-run scratch directories, compares each with its working file, and prints a diff for each stale page. Check mode never rewrites a page. --write replaces the four pages, with the same clean-tree rule as rust_fmt.sh.
• dev/update_config_docs.sh and dev/update_function_docs.sh gain --output-dir DIR, so the checker reuses the existing generators and headers. Without the option, both scripts behave as before.
• dev/rust_lint.sh runs the checker as a write step.
• The config-docs-check job runs the checker and keeps its git diff --exit-code guard. The job identity and setup do not change.
• docs/source/contributor-guide/testing.md documents the check and the update command.

What is the testing strategy for this PR?

• In a clean clone with the real generators: the no-argument scripts and --output-dir produce byte-identical pages, the four committed pages pass, a committed stale page fails with its diff, --write restores it byte for byte, the dirty-tree gate refuses, and staged edits survive check mode. No lockfile changed.
• A fixture with stub cargo and npx covered each page stale on its own, generator and formatter failures in both modes, cleanup after failure and interruption, concurrent runs, missing npx, comparison errors, and argument errors. No page changed in any failure case.
• The parsed workflow matches main except the replaced steps. The full ./dev/rust_lint.sh passes.

Are there any user-facing changes?

No.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.40%. Comparing base (b4a8c82) to head (b88d405).
⚠️ Report is 14 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25525      +/-   ##
==========================================
+ Coverage   82.38%   82.40%   +0.01%     
==========================================
  Files        1138     1138              
  Lines      434328   434951     +623     
  Branches   434328   434951     +623     
==========================================
+ Hits       357824   358406     +582     
+ Misses      54872    54844      -28     
- Partials    21632    21701      +69     

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[alamb]

Thank you @kumarUjjawal -- this is a nice change in my mind.

I had a suggestion for some improvements but I don't think they are needed

[alamb]

Minor: I suggest calling this check_generated_docs.sh as it is both shorter and more general

[alamb]

Can we also please make file references github url links so it is easier to follow what is going on?

ALso I think a bunch of details of the implementation are irrelevant for people running this check (e.g. that needs cargo and npx ,etc) is irrelevant here -- we could just say somehting like

To check they are up to date, run the ci/scripts/check_config_function_docs.sh script, which is also run as part of ./dev/rust_lint.sh

[kumarUjjawal]

Thank you @alamb for suggestions.