Improve formatting of inline documentation for `get_pages()`.

Adds missing default values, corrects several argument types, backtick-escapes argument names used in descriptions.

See #28298.


git-svn-id: https://develop.svn.wordpress.org/trunk@30725 602fd350-edb4-49c9-b593-d223f7449a82
Only backtick-escape individual HTML entities in the DocBlock for `wp_kses_normalize_entities()`.

Props TobiasBg.
Fixes #30473.


git-svn-id: https://develop.svn.wordpress.org/trunk@30726 602fd350-edb4-49c9-b593-d223f7449a82