style(lib/rules): var -> const & let (#4493)

Just like #4451 but for
`lib/rules`. This is the last of `lib/*`

Smaller part of the full vision:
#4444

---------

Co-authored-by: Wilco Fiers <WilcoFiers@users.noreply.github.com>

lib/rules/data-table-large-matches.js

@@ -2,7 +2,7 @@ import { isDataTable, toArray } from '../commons/table';
 
 function dataTableLargeMatches(node) {
   if (isDataTable(node)) {
-    var tableArray = toArray(node);
+    const tableArray = toArray(node);
     return (
       tableArray.length >= 3 &&
       tableArray[0].length >= 3 &&

lib/rules/frame-title-has-text-matches.js

@@ -1,7 +1,7 @@
 import { sanitize } from '../commons/text';
 
 function frameTitleHasTextMatches(node) {
-  var title = node.getAttribute('title');
+  const title = node.getAttribute('title');
   return !!sanitize(title);
 }
 

lib/rules/label-matches.js

@@ -6,7 +6,7 @@ function labelMatches(node, virtualNode) {
     return true;
   }
 
-  var type = virtualNode.attr('type').toLowerCase();
+  const type = virtualNode.attr('type').toLowerCase();
   return (
     ['hidden', 'image', 'button', 'submit', 'reset'].includes(type) === false
   );

lib/rules/link-in-text-block-matches.js

@@ -2,8 +2,8 @@ import { sanitize } from '../commons/text';
 import { isVisibleOnScreen, isInTextBlock } from '../commons/dom';
 
 function linkInTextBlockMatches(node) {
-  var text = sanitize(node.innerText);
-  var role = node.getAttribute('role');
+  const text = sanitize(node.innerText);
+  const role = node.getAttribute('role');
 
   if (role && role !== 'link') {
     return false;