feat: add selecting/copying column names

Author: lucien martijn

media/styles/parquet-visualizer.css

@@ -50,6 +50,13 @@ body {
     box-sizing: border-box;
 }
 
+.tabulator-headers {
+    user-select: text !important;
+    -webkit-user-select: text !important;
+    -moz-user-select: text !important;
+    -ms-user-select: text !important;
+}
+
 @media (max-width: 1024px) and (min-width: 769px) {
     #editor {
         height: 25%;