fix: Remove underline from trailing whitespace in external links

Removes the non-breaking space that caused underlines to appear below
trailing whitespace between external icon and link text. Replaces it
with margin-inline-start.

AWSUI-60840

Author: xyos

src/link/internal.tsx

@@ -186,7 +186,6 @@ const InternalLink = React.forwardRef(
         {children}
         {external && (
           <span className={styles['icon-wrapper']}>
-            &nbsp;
             <span
               className={styles.icon}
               aria-label={renderedExternalIconAriaLabel}

src/link/styles.scss

@@ -58,6 +58,11 @@
 
 .icon-wrapper {
   white-space: nowrap;
+  /* Add non-breaking space for consistent spacing */
+  &::before {
+    content: '\a0';
+    display: inline-block;
+  }
 }
 
 .icon {