fix(actions): Handle missing poll object

[Jiralite]

Please describe the changes this PR makes and why it should be merged:
poll will be missing if GUILD_MESSAGE_POLLS is enabled but MESSAGE_CONTENT is not, or if a message containing a poll was uncached but the appropriate partials were enabled. This caused a crash:

/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/packages/discord.js/src/client/actions/MessagePollVoteRemove.js:16
    const answer = poll.answers.get(data.answer_id);
                        ^

TypeError: Cannot read properties of null (reading 'answers')
    at MessagePollVoteRemoveAction.handle (/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/packages/discord.js/src/client/actions/MessagePollVoteRemove.js:16:25)
    at module.exports [as MESSAGE_POLL_VOTE_REMOVE] (/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/packages/discord.js/src/client/websocket/handlers/MESSAGE_POLL_VOTE_REMOVE.js:4:40)
    at WebSocketManager.handlePacket (/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/packages/discord.js/src/client/websocket/WebSocketManager.js:355:31)
    at WebSocketManager.<anonymous> (/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/packages/discord.js/src/client/websocket/WebSocketManager.js:239:12)
    at WebSocketManager.emit (/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/node_modules/.pnpm/@[email protected]/node_modules/@vladfrangu/async_event_emitter/src/index.ts:360:28)
    at WebSocketShard.<anonymous> (/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/packages/ws/src/strategies/sharding/SimpleShardingStrategy.ts:32:47)
    at WebSocketShard.emit (/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/node_modules/.pnpm/@[email protected]/node_modules/@vladfrangu/async_event_emitter/src/index.ts:360:28)
    at WebSocketShard.onMessage (/Users/jiralite/Documents/code/GitHub/discordjs/discord.js/packages/ws/src/ws/WebSocketShard.ts:640:10)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)

The optional chaining operator will be enough to cause an exit on the next line with no error.
Status and versioning classification:

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
discord-js	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 11, 2024 8:44am

1 Ignored Deployment

Name	Status	Preview	Comments	Updated (UTC)
discord-js-guide	⬜️ Ignored (Inspect)	Visit Preview		May 11, 2024 8:44am