Docs Formatting: Backtick-escape inline code for all dynamic hook docs in wp-admin/*.

Also includes some changes to move hook docs to directly precede hook lines. This is necessary to prevent DocBlock-matching confusion when core is parsed.

Affects DocBlocks for the following hooks:
* `wp_ajax_ . $_REQUEST['action']`
* `wp_ajax_nopriv_ . $_REQUEST['action']`
* `admin_footer- . $GLOBALS['hook_suffix']`
* `admin_head-$hook_suffix`
* `admin_post_nopriv_{$action}`
* `admin_post_{$action}`
* `load-  . $page_hook`
* `load- . $plugin_page`
* `load-importer- . $importer`
* `load- . $pagenow`
* `admin_action_ . $_REQUEST['action']`
* `async_upload_{$type}`
* `add_meta_boxes_ . $post_type`
* `{$taxonomy}_pre_edit_form`
* `{$taxonomy}_term_edit_form_tag`
* `{$taxonomy}_edit_form_fields`
* `{$taxonomy}_edit_form`
* `after-{$taxonomy}-table`
* `{$taxonomy}_pre_add_form`
* `{$taxonomy}_term_new_form_tag`
* `{$taxonomy}_add_form_fields`
* `{$taxonomy}_add_form`
* `media_upload_$type`
* `media_upload_$tab`
* `install_plugins_pre_$tab`
* `install_plugins_$tab`
* `install_themes_pre_{$tab}`
* `install_themes_{$tab}`
* `update-core-custom_{$action}`
* `update-custom_{$action}`
* `user_{$name}_label`

See #30552.


git-svn-id: https://develop.svn.wordpress.org/trunk@30649 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/plugin-install.php

@@ -57,7 +57,7 @@ $body_id = $tab;
 /**
  * Fires before each tab on the Install Plugins screen is loaded.
  *
- * The dynamic portion of the action hook, $tab, allows for targeting
+ * The dynamic portion of the action hook, `$tab`, allows for targeting
  * individual tabs, for instance 'install_plugins_pre_plugin-information'.
  *
  * @since 2.7.0
@@ -117,15 +117,14 @@ if ( $tab !== 'upload' ) {
 /**
  * Fires after the plugins list table in each tab of the Install Plugins screen.
  *
- * The dynamic portion of the action hook, $tab, allows for targeting
+ * The dynamic portion of the action hook, `$tab`, allows for targeting
  * individual tabs, for instance 'install_plugins_plugin-information'.
  *
  * @since 2.7.0
  *
  * @param int $paged The current page number of the plugins list table.
  */
-?>
-<?php do_action( "install_plugins_$tab", $paged ); ?>
+do_action( "install_plugins_$tab", $paged ); ?>
 </div>
 <?php
 /**