docs(storybook): add temp fix for duplicate names

Storybook overrides properties with slots if they share a name.
We fix this by adding the word 'slot' to duplicate slot names.
This is a Storybook-only fix that does not change anything runtime.

Author: iOvergaard

.storybook/preview.js

@@ -52,12 +52,20 @@ setCustomElements(customElements);
 
 function WebComponentFormatter(customElements) {
   for (let tag of customElements.tags || []) {
+    // Find all names of properties
+    const propertyNames = (tag.properties || []).map(p => p.name);
+
     for (let slot of tag.slots || []) {
       // Replace the name of the default slot so Storybook will show it
       if (typeof slot.name === 'string' && slot.name.length === 0) {
         slot.name = 'slot';
       }
 
+      // If the slot has the same name as a property, then add the word 'slot' to the name
+      if (propertyNames.includes(slot.name)) {
+        slot.name = `${slot.name} slot`;
+      }
+
       // Set type of slots
       if (typeof slot.type === 'undefined' || slot.type.length === 0) {
         slot.type = 'HTMLElement';