Feishu bot commands

What does this MR do and why?

Related to #474 (closed), this MR is followed !873 (merged)

The whole tasks are in here: #474 (comment 1152476).

1. Add Gitlab::Chatops::BaseBotHandler to process the same logic of all channels like Dingtalk and Feishu.
2. Add Gitlab::Chatops::FeishuBotHandler to process the logic of Feishu.
3. Add Gitlab::Feishu::Formatter to process the message Formatter of Feishu.

Screenshots or screen recordings

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How to set up and validate locally

Follow up the docs like Dingtalk Bot: https://docs.gitlab.cn/jh/user/project/integrations/dingtalk_command.html