[WIP]feat: option loaders to generate kitex options

[BaiZe1998]

• ServerOptionLoader
• ClientOptionLoader
• StreamClientOptionLoader
• CalloptOptionLoader
• StreamCallOptionLoader
• Unit Test

[bytedance-oss-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: BaiZe1998

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[DMwangnima]

What about changing this interface to Load(cfg *config.ServerConfig) ([]server.Option, error) and transfer the logic from NewServerOptionLoader to Load?

Not only would one optionLoader support multiple configs, but it would also be able to call each Translator to get the options while iterating through the config.

[BaiZe1998]

Something like that?

func NewServerOptionLoader() OptionLoader {
    return &DefaultOptionLoader{
	translators:make([]Translator, 0),
    }
}

func (loader *DefaultOptionLoader) Load(config *config.ServerConfig) ([]server.Option, error) {
    if config == nil {
	return nil, fmt.Errorf("server config not set")
    }
    // generate translators from config
    // ....
    var options []server.Option
    for _, trans := range loader.translators {
	options = append(options, trans(config))
    }
    return options, nil
}