Don't show header in spectrum table unless rows exist

packages/bbui/src/Table/Table.svelte

@@ -153,6 +153,7 @@
     class="container">
     <div style={contentStyle}>
       <table class="spectrum-Table" class:spectrum-Table--quiet={quiet}>
+        {#if sortedRows?.length}
           <thead class="spectrum-Table-head">
             <tr>
               {#if showEditColumn}
@@ -200,6 +201,7 @@
               {/each}
             </tr>
           </thead>
+        {/if}
         <tbody class="spectrum-Table-body">
           {#if sortedRows?.length}
             {#each sortedRows as row, idx}