layouts: Change "small"-outline to "small-row"-outline in terminal-layouts

and change the font-size for the "small"-outline back to 0.5em,
so that the font-size for custom-layouts that use it does not change.

Part-of: <https://gitlab.gnome.org/World/Phosh/squeekboard/-/merge_requests/704>

data/common.css

@@ -58,6 +58,10 @@ sq_button.action {
 }
 
 sq_button.small {
+    font-size: 0.5em;
+}
+
+sq_button.small-row {
     font-size: 0.575em;
 }