Add queue clear command

src/commands/clear.ts

@@ -0,0 +1,22 @@
+import {Message} from 'discord.js';
+import {TYPES} from '../types';
+import {inject, injectable} from 'inversify';
+import Queue from '../services/queue';
+import Command from '.';
+
+@injectable()
+export default class implements Command {
+  public name = 'clear';
+  public description = 'clears all songs in queue (except currently playing)';
+  private readonly queue: Queue;
+
+  constructor(@inject(TYPES.Services.Queue) queue: Queue) {
+    this.queue = queue;
+  }
+
+  public async execute(msg: Message, _: string []): Promise<void> {
+    this.queue.clear(msg.guild!.id);
+
+    await msg.channel.send('cleared');
+  }
+}