Refactor ZenKeyboardShortcutsLoader to add a new method for removing shortcuts and update the resetAllShortcuts method to use it

src/ZenKeyboardShortcuts.mjs

@@ -493,6 +493,10 @@ class ZenKeyboardShortcutsLoader {
   async load(withoutCache = false) {
     return (await this.loadObject(withoutCache))?.shortcuts;
   }
+
+  async remove() {
+    await IOUtils.remove(this.shortcutsFile);
+  }
 }
 
 function zenGetDefaultShortcuts() {
@@ -777,6 +781,10 @@ var gZenKeyboardShortcutsManager = {
     }
   },
 
+  async resetAllShortcuts() {
+    await this.loader.remove();
+  },
+
   async _saveShortcuts() {
     let json = [];
     for (shortcut of this._currentShortcutList) {