feat: migrate to viper library for config manage

[bzp2010]

Feature request

Please describe your feature

At present, the original yaml file is directly read and unmarshal mode is used for configuration management. If a new configuration item is added, multiple codes will be modified, and if the old configuration is changed, it will be incompatible.

Describe the solution you'd like

Use github.com/spf13/viper to manage configurations. (It uses MIT license, we should be able to import it.)

It supports the use of yaml and JSON format configuration files, or configuration based on environment variables. At the same time, it can also provide etcd based configuration management function.

Improvement Roadmap

1. First, only change conf.go to unmarshal the configuration file into the structure pointer by viper, which will not destroy the compatibility of the old program.

2. Then, use Viper to get the configuration file in the newly written code.

3. Finally, gradually modify the old code to read the configuration code.

[github-actions]

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