Fix lock icon by adding lock domain

Fixes #41

src/cards/LockCard.js

@@ -0,0 +1,39 @@
+import {AbstractCard} from "./AbstractCard";
+
+/**
+ * Lock Card Class
+ *
+ * Used to create a card for controlling an entity of the lock domain.
+ *
+ * @class
+ * @extends AbstractCard
+ */
+class LockCard extends AbstractCard {
+  /**
+   * Default options of the card.
+   *
+   * @type {lockCardOptions}
+   * @private
+   */
+  #defaultOptions = {
+    type: "custom:mushroom-lock-card",
+    icon: undefined,
+  };
+
+  /**
+   * Class constructor.
+   *
+   * @param {hassEntity} entity The hass entity to create a card for.
+   * @param {lockCardOptions} [options={}] Options for the card.
+   * @throws {Error} If the Helper module isn't initialized.
+   */
+  constructor(entity, options = {}) {
+    super(entity);
+    this.mergeOptions(
+        this.#defaultOptions,
+        options,
+    );
+  }
+}
+
+export {LockCard};

src/cards/MediaPlayerCard.js

@@ -17,6 +17,7 @@ class MediaPlayerCard extends AbstractCard {
    */
   #defaultOptions = {
     type: "custom:mushroom-media-player-card",
+    icon: undefined,
     use_media_info: true,
     media_controls: [
       "on_off",

src/optionDefaults.js

@@ -86,6 +86,11 @@ export const optionDefaults = {
       showControls: false,
       hidden: false,
     },
+    lock: {
+      title: "Locks",
+      showControls: false,
+      hidden: false,
+    },
     climate: {
       title: "Climates",
       showControls: false,