Coding Standards: Improve readability of wp-admin/options-permalink.php.

Includes: 
* Wrapping longer lines and reducing alignment levels to fit more data on the screen.
* Restoring `esc_attr()` for input values, which may include translatable parts.
* Adding comments to closing `</div>` tags and PHP `endif` statements.
* Reducing the context switching between HTML and PHP.
* Balancing PHP conditionals to better reflect the structure.
* Removing repeated function calls to improve performance.
* Renaming some variables for clarity and consistency.

Follow-up to [470], [601], [963], [1227], [1664], [2746], [3029], [6976], [7230], [11350], [14051], [14553], [21891], [34691], [34749], [37747], [38066], [41182], [41986], [42343], [43571], [48710], [50830], [51892], [53706].

See #55647.

git-svn-id: https://develop.svn.wordpress.org/trunk@53710 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-admin/css/forms.css

@@ -1085,7 +1085,6 @@ table.form-table td .updated p {
 
 .form-table.permalink-structure .structure-selection .row > div {
 	max-width: calc(100% - 24px);
-	margin-left: 4px;
 	display: inline-flex;
 	flex-direction: column;
 }