Add Fault injection filter

[mark4z]

What would you like to be added:
A Fault injection filter should provide configurable error injection capabilities, such as delay, error local reply. it is best to have more detailed routing-based configuration capabilities

Why is this needed:
Because this is the ability that is required in the testing phase

How to:
A simple example :
pkg/filter/authority/authority.go

ctxc.SendLocalReply will be useful in this new filter.

func (f *Filter) Decode(c *http.HttpContext) filter.FilterStatus {
	for _, r := range f.cfg.Rules {
		item := c.GetClientIP()
		if r.Limit == App {
			item = c.GetApplicationName()
		}

		result := passCheck(item, r)
		if !result {
			c.SendLocalReply(nh.StatusForbidden, constant.Default403Body)
			return filter.Stop
		}
	}
	return filter.Continue
}

[mark4z]

close via #571