Clarify documentation for hooks in `sanitize_post_field()`.

* `edit_post_{$field}` pairs with `edit_{$field}`
* `pre_post_{$field}` pairs with `pre_{$field}`
* `post_{$field}` pairs with `{$field}`

As the above pairs' docs are unnecessarily duplicative, the second sets of docs have been removed. Also, the "duplicates" are purposely not marked as such in this case as the hook names differ. Also remove `@deprecated` tags mistakenly left in in [28041].

See #25376.


git-svn-id: https://develop.svn.wordpress.org/trunk@28042 602fd350-edb4-49c9-b593-d223f7449a82
DFW:
- Move the word count and "Just Write" to a fixed bar at the bottom.
- Fix responsive mode to 480px. Narrower screens will have a scroll bar.
- Hide the Help button on screens < 480px, move the Save button to the right, make it bigger to match the others, and other responsive mode fixes.
Fixes #26907, see #27709

git-svn-id: https://develop.svn.wordpress.org/trunk@28043 602fd350-edb4-49c9-b593-d223f7449a82