settings ui: move security key credential management checkboxes

This changes the chrome://settings/securityKeys credential management list
layout from "website | username | checkbox" to "checkbox | website | username".

Bug: 1008903
Change-Id: Id4f5b0b0e0a392dc3948f6f4ec49f076fc592888
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1872443
Auto-Submit: Martin Kreichgauer <martinkr@google.com>
Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#709668}

chrome/browser/resources/settings/privacy_page/security_keys_credential_management_dialog.html

@@ -76,9 +76,9 @@
 
           <div id="credentials">
             <div id="header" class="list-item column-header">
+              <div class="checkbox-placeholder"></div>
               <div class="site">$i18n{securityKeysCredentialWebsite}</div>
               <div class="user">$i18n{securityKeysCredentialUsername}</div>
-              <div class="checkbox-placeholder"></div>
             </div>
 
             <div id="container">
@@ -86,16 +86,16 @@
                   class="cr-separators list-with-header">
                 <template>
                   <div class="list-item">
+                    <cr-checkbox on-change="checkedCredentialsChanged_"
+                        data-id$="[[item.id]]"
+                        checked="[[credentialIsChecked_(item.id)]]"
+                        disabled="[[deleteInProgress_]]"></cr-checkbox>
                     <div class="site" aria-label="[[item.relyingPartyId]]">
                       <site-favicon url="[[item.relyingPartyId]]">
                       </site-favicon>
                       <div>[[item.relyingPartyId]]</div>
                     </div>
                     <div class="user">[[formatUser_(item)]]</div>
-                    <cr-checkbox on-change="checkedCredentialsChanged_"
-                        data-id$="[[item.id]]"
-                        checked="[[credentialIsChecked_(item.id)]]"
-                        disabled="[[deleteInProgress_]]"></cr-checkbox>
                   </div>
                 </template>
               </iron-list>