Add .caption-top for tables (#30435)

* Move caption-side to <table> element in Reboot

* Add class for .caption-top

scss/_reboot.scss

@@ -355,6 +355,7 @@ svg {
 // Prevent double borders
 
 table {
+  caption-side: bottom;
   border-collapse: collapse;
 }
 
@@ -363,7 +364,6 @@ caption {
   padding-bottom: $table-cell-padding;
   color: $table-caption-color;
   text-align: left;
-  caption-side: bottom;
 }
 
 // 1. Matches default `<td>` alignment by inheriting `text-align`.

scss/_tables.scss

@@ -30,6 +30,13 @@
 }
 
 
+//
+// Change placement of captions with a class
+//
+
+.caption-top { caption-side: top; }
+
+
 //
 // Condensed table w/ half padding
 //