refactor: move Guild setPositions methods to managers (#6875)

Co-authored-by: Jiralite <33201955+Jiralite@users.noreply.github.com>

src/managers/GuildChannelManager.js

@@ -192,6 +192,31 @@ class GuildChannelManager extends CachedManager {
     return channels;
   }
 
+  /**
+   * Batch-updates the guild's channels' positions.
+   * <info>Only one channel's parent can be changed at a time</info>
+   * @param {ChannelPosition[]} channelPositions Channel positions to update
+   * @returns {Promise<Guild>}
+   * @example
+   * guild.channels.setPositions([{ channel: channelId, position: newChannelIndex }])
+   *   .then(guild => console.log(`Updated channel positions for ${guild}`))
+   *   .catch(console.error);
+   */
+  async setPositions(channelPositions) {
+    channelPositions = channelPositions.map(r => ({
+      id: this.client.channels.resolveId(r.channel),
+      position: r.position,
+      lock_permissions: r.lockPermissions,
+      parent_id: typeof r.parent !== 'undefined' ? this.channels.resolveId(r.parent) : undefined,
+    }));
+
+    await this.client.api.guilds(this.id).channels.patch({ data: channelPositions });
+    return this.client.actions.GuildChannelsPositionUpdate.handle({
+      guild_id: this.id,
+      channels: channelPositions,
+    }).guild;
+  }
+
   /**
    * Obtains all active thread channels in the guild from Discord
    * @param {boolean} [cache=true] Whether to cache the fetched data