Fix template-no-whitespace-for-layout false positive on attribute values

The rule's GlimmerTextNode visitor fired on attribute value text nodes
(e.g. `<div class="foo  bar">`), reporting layout-whitespace violations
for consecutive spaces inside class lists and other attribute values.

Upstream ember-template-lint only visits body text, since its HBS
parser exposes attribute values differently. Skip GlimmerTextNodes
whose parent is a GlimmerAttrNode.

Author: johanrd

lib/rules/template-no-whitespace-for-layout.js

@@ -27,6 +27,13 @@ module.exports = {
 
     return {
       GlimmerTextNode(node) {
+        // Ember's Glimmer parser emits attribute values (e.g. `class="foo  bar"`)
+        // as GlimmerTextNode children of a GlimmerAttrNode. Whitespace there is
+        // part of the attribute value, not layout whitespace between words.
+        if (node.parent?.type === 'GlimmerAttrNode') {
+          return;
+        }
+
         const text = sourceCode.getText(node);
         if (!text) {
           return;

tests/lib/rules/template-no-whitespace-for-layout.js

@@ -18,6 +18,9 @@ const validHbs = [
 >
   example
 </div>`,
+  // Whitespace inside attribute values (e.g. Tailwind class lists) is not layout whitespace.
+  '<div class="foo  bar"></div>',
+  '<div class="min-h-dvh bg-gray-200  "></div>',
 ];
 
 const invalidHbs = [