Custom log formatter secondpr

[IamCathal]

Second PR of the custom log formatter. I found this one to be very closely coupled to the third part so I found it quite hard. LogFormatter is implemented but no custom formatting is implemented yet which will come in the third PR.

Most of the work will come in the third actually so this pr isn't very important at all

Works fully with

package main

import (
	beego "github.com/astaxie/beego/pkg"
	"github.com/astaxie/beego/pkg/logs"
)

type MainController struct {
	beego.Controller
}

func main() {
	// ctrl := &MainController{}
	// beego.Router("/yuppa", ctrl, "get:Yuppa")
	beego.BConfig.Log.AccessLogs = true
	beego.BConfig.Log.AccessLogsFormat = "JSON_FORMAT"
	logs.SetLogger("console", "")
	logs.SetLogger("file", `{"filename":"test.json"}`)

	logs.EnableFullFilePath(true)
	logs.EnableFuncCallDepth(true)
	beego.Run()
}

[IamCathal]

CI failed on second build. This failure below usually seems to happen so I'm not sure what the problem is:

unable to WriteMsg to adapter:conn,error:dial tcp :7020: connect: connection refused
--- FAIL: TestReconnect (0.00s)

I'll push another commit and see if it fixes itself

[flycash]

Thank you!
Next PR maybe we could focus on:
How users register their custom LogFormat and how all implementations use those LogFormat?

[flycash]

CI failed on second build. This failure below usually seems to happen so I'm not sure what the problem is:

unable to WriteMsg to adapter:conn,error:dial tcp :7020: connect: connection refused
--- FAIL: TestReconnect (0.00s)

I'll push another commit and see if it fixes itself

Just ignore this error. This unit test is not stable. I can retry CI until it success.

[IamCathal]

Yes so the last PR will be the full implementation of users setting their own formatters right?

Just to get this right the order for the formatters should go as follows:

adapter-specific formatter > global formatter > default formatter

So using SetLoggerWithOpts overrides a global set formatter and that also overrides any default set formatter.

[IamCathal]

I'll write up a PR with the new logging documentation on beedoc after I finish this next PR.

[flycash]

Just kindly remind you that I create a new branch named "ftr/log_format" and please use this branch as base branch.