gh-62172: Document undocumented public functions in inspect

[sreehariannam]

Adds documentation for public, __all__-exported functions in the inspect module that were missing from Doc/library/inspect.rst:

• inspect.getabsfile()
• inspect.indentsize()
• inspect.classify_class_attrs()
• inspect.findsource()
• inspect.getblock()
• inspect.walktree()
• inspect.getargs()
• inspect.formatannotation()
• inspect.formatannotationrelativeto()
• inspect.getlineno()

Closes gh-62172. This was originally split across multiple PRs (#153628, #154534, #154536); per review feedback, all of the changes have been consolidated into this single PR.

Verified with sphinx-lint (no issues) against the current Doc/library/inspect.rst.

[python-cla-bot]

All commit authors signed the Contributor License Agreement.

[read-the-docs-community]

Documentation build overview

📚 cpython-previews | 🛠️ Build #33745783 | 📁 Comparing 1b58423 against main (dd2faeb)

  🔍 Preview build  

58 files changed · ± 58 modified

± Modified

• c-api/exceptions.html
• c-api/frame.html
• c-api/type.html
• c-api/typeobj.html
• c-api/veryhigh.html
• faq/general.html
• howto/abi3t-migration.html
• howto/logging-cookbook.html
• library/allos.html
• library/annotationlib.html
• and 48 more...

[sreehariannam]

Thanks for the review! Addressed both points in the latest commit: dropped the normcase implementation detail from getabsfile's description, and linked named tuple via :term: in classify_class_attrs.

[picnixz]

Please incorporate the other docs changes in this PR. There is no need for multiple ones.

[sreehariannam]

Consolidated the docs for findsource, getblock, walktree, getargs, formatannotation, formatannotationrelativeto, and getlineno into this PR as requested, alongside the original getabsfile, indentsize, and classify_class_attrs entries. Closing #153628, #154534, and #154536 in favor of this one.