[venus*] 增减健康检查的接口， 适应一些负载均衡服务用于自动检查。

[hunjixin]

Checklist

• This is not a new feature or an enhancement to the Filecoin protocol. If it is, please open an FIP issue.
• This is not a new feature request. If it is, please file a feature request instead.
• This is not brainstorming ideas. If you have an idea you'd like to discuss, please open a new discussion on the venus forum and select the category as Ideas.
• I have a specific, actionable, and well motivated improvement to propose.

Venus component

• venus daemon - [chain service] chain sync
• venus auth - [chain service] authentication
• venus messager - [chain service] message management (mpool)
• venus gateway - [chain service] gateway
• venus miner - [chain service] mining and block production
• venus sealer/worker - sealing
• venus sealer - proving (WindowPoSt)
• venus market - storage deal
• venus market - retrieval deal
• venus market - data transfer
• venus light-weight client
• venus JSON-RPC API
• Other

Improvement Suggestion

增加 /healthcheck GET接口，返回200状态码，用于负载均衡服务进行健康检查。

[hunjixin]

用于探测接口服务是否启动， dial无法应对port forwarding的情况