Bug 1865433 - Cards View: move expand/collapse button to third row. r=sol

- Move expand/collapse button to third row.
- Remove extra spacing before Group by Sort header.
- Expand button affects Thread View and Group by Sort.

Differential Revision: https://phabricator.services.mozilla.com/D193972

--HG--
extra : moz-landing-system : lando

mail/base/content/about3Pane.xhtml

@@ -281,16 +281,16 @@
           </div>
           <div class="thread-card-row">
             <div class="thread-card-subject-container">
-              <button type="button"
-                      class="button button-flat button-reset twisty"
-                      aria-hidden="true"
-                      tabindex="-1">
-                <img src="" alt="" class="twisty-icon" />
-              </button>
               <span class="subject"></span>
             </div>
           </div>
           <div class="thread-card-row">
+            <button type="button"
+                    class="button button-flat button-reset twisty"
+                    aria-hidden="true"
+                    tabindex="-1">
+              <img src="" alt="" class="twisty-icon" />
+            </button>
             <div class="thread-card-icon-info">
               <img class="attachment-icon" src="" data-l10n-id="tree-list-view-row-attach" />
               <div class="thread-card-tags-info">

mail/themes/shared/mail/threadPane.css

@@ -865,10 +865,6 @@ tr[is="thread-card"] {
   text-overflow: ellipsis;
 }
 
-[data-properties~="dummy"] .thread-card-subject-container .subject {
-  padding-inline-start: 9px;
-}
-
 .thread-card-container .date {
   flex: 0 0 auto;
   white-space: nowrap;