feat: add fields with logx methods, support using third party logging libs. (#1847)

* backup

* simplify

* chore: remove unused pool

* chore: fix lint errors

* chore: use strings.Builder instead of bytes.Buffer

* test: add more tests

* chore: fix reviewdog

* test: fix data race

* feat: make logger customizable

* chore: fix reviewdog

* test: fix fails

* chore: fix set writer twice

* chore: use context instead of golang.org context

* chore: specify uint32 for level types

core/logx/vars.go

@@ -0,0 +1,60 @@
+package logx
+
+import "errors"
+
+const (
+	// InfoLevel logs everything
+	InfoLevel uint32 = iota
+	// ErrorLevel includes errors, slows, stacks
+	ErrorLevel
+	// SevereLevel only log severe messages
+	SevereLevel
+)
+
+const (
+	jsonEncodingType = iota
+	plainEncodingType
+
+	jsonEncoding     = "json"
+	plainEncoding    = "plain"
+	plainEncodingSep = '\t'
+)
+
+const (
+	accessFilename = "access.log"
+	errorFilename  = "error.log"
+	severeFilename = "severe.log"
+	slowFilename   = "slow.log"
+	statFilename   = "stat.log"
+
+	consoleMode = "console"
+	volumeMode  = "volume"
+
+	levelAlert  = "alert"
+	levelInfo   = "info"
+	levelError  = "error"
+	levelSevere = "severe"
+	levelFatal  = "fatal"
+	levelSlow   = "slow"
+	levelStat   = "stat"
+
+	backupFileDelimiter = "-"
+	flags               = 0x0
+)
+
+const (
+	callerKey    = "caller"
+	contentKey   = "content"
+	durationKey  = "duration"
+	levelKey     = "level"
+	spanKey      = "span"
+	timestampKey = "@timestamp"
+	traceKey     = "trace"
+)
+
+var (
+	// ErrLogPathNotSet is an error that indicates the log path is not set.
+	ErrLogPathNotSet = errors.New("log path must be set")
+	// ErrLogServiceNameNotSet is an error that indicates that the service name is not set.
+	ErrLogServiceNameNotSet = errors.New("log service name must be set")
+)