Fix timestamp's position on the chat panel with a maximized widget in IRC layout (#8464)

Fix avatar's position on the chat panel with a maximized widget in IRC layout
Fix timestamp's position on Message Edits history modal window

Also:
- Align DisambiguatedProfile with reactions row and thread summary with a variable
- Add width property as default
- Use the global variable on _IRCLayout.scss

Signed-off-by: Suguru Hirahara <luixxiul@users.noreply.github.com>

res/css/views/dialogs/_MessageEditHistoryDialog.scss

@@ -55,6 +55,12 @@ limitations under the License.
         text-decoration: underline;
     }
 
+    .mx_EventTile {
+        .mx_MessageTimestamp {
+            position: absolute;
+        }
+    }
+
     .mx_EventTile_line, .mx_EventTile_content {
         margin-right: 0px;
     }