#20511: fix: register poll action gate for Telegram adapter (#17528)

The Telegram message action adapter was missing the poll action gate and handler. Users with polls enabled in their Telegram action config could not create polls through the agent. - Add `polls` field to `TelegramActionConfig` type - Register `poll` in `listActions` when `gate("polls")` is true - Add poll action handler using `sendPollTelegram` <!-- greptile_comment --> <h3>Greptile Summary</h3> Added the missing `polls` field to `TelegramActionConfig` and registered the poll action gate in the Telegram message adapter, enabling users to create polls when configured. The implementation follows the same pattern used for other Telegram actions like `sticker` and `createForumTopic`, and correctly uses the existing `sendPollTelegram` function. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The changes are minimal and follow established patterns in the codebase. The implementation correctly adds the missing poll action gate registration, uses existing infrastructure (`sendPollTelegram`), and matches the implementation pattern used for other Telegram actions like stickers and forum topics. The type definition is consistent with Discord's `DiscordActionConfig`. - No files require special attention _{Last reviewed commit: d402679} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->