feat(WelcomeScreen): welcome screens (#5490)

Co-authored-by: Jan <66554238+vaporox@users.noreply.github.com>
Co-authored-by: izexi <43889168+izexi@users.noreply.github.com>
Co-authored-by: SpaceEEC <spaceeec@yahoo.com>
Co-authored-by: Vlad Frangu <kingdgrizzle@gmail.com>

src/structures/WelcomeScreen.js

@@ -0,0 +1,48 @@
+'use strict';
+
+const Base = require('./Base');
+const WelcomeChannel = require('./WelcomeChannel');
+const Collection = require('../util/Collection');
+
+/**
+ * Represents a welcome screen.
+ * @extends {Base}
+ */
+class WelcomeScreen extends Base {
+  constructor(guild, data) {
+    super(guild.client);
+
+    /**
+     * The guild for this welcome screen
+     * @type {Guild}
+     */
+    this.guild = guild;
+
+    /**
+     * The description of this welcome screen
+     * @type {?string}
+     */
+    this.description = data.description ?? null;
+
+    /**
+     * Collection of welcome channels belonging to this welcome screen
+     * @type {Collection<Snowflake, WelcomeChannel>}
+     */
+    this.welcomeChannels = new Collection();
+
+    for (const channel of data.welcome_channels) {
+      const welcomeChannel = new WelcomeChannel(this.guild, channel);
+      this.welcomeChannels.set(welcomeChannel.channelID, welcomeChannel);
+    }
+  }
+
+  /**
+   * Whether the welcome screen is enabled on the guild or not
+   * @type {boolean}
+   */
+  get enabled() {
+    return this.guild.features.includes('WELCOME_SCREEN_ENABLED');
+  }
+}
+
+module.exports = WelcomeScreen;