Move cli/logger to shared, and refactor all its usages in cli (#349)

* Move `cli/logger` to `shared`, and refactor all its usages in `cli`

* Remove indirect for `op/go-logging` in `shared`

shared/logger/logger.go

@@ -0,0 +1,30 @@
+package logger
+
+import (
+	"os"
+
+	"github.com/op/go-logging"
+)
+
+var Log = logging.MustGetLogger("mizu")
+
+var format = logging.MustStringFormatter(
+	`%{time} %{level:.5s} ▶ %{pid} %{shortfile} %{shortfunc} ▶ %{message}`,
+)
+
+func InitLogger(logPath string) {
+	f, err := os.OpenFile(logPath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+	if err != nil {
+		Log.Infof("Failed to open mizu log file: %v, err %v", logPath, err)
+	}
+
+	fileLog := logging.NewLogBackend(f, "", 0)
+	consoleLog := logging.NewLogBackend(os.Stderr, "", 0)
+
+	backend2Formatter := logging.NewBackendFormatter(fileLog, format)
+
+	backend1Leveled := logging.AddModuleLevel(consoleLog)
+	backend1Leveled.SetLevel(logging.INFO, "")
+
+	logging.SetBackend(backend1Leveled, backend2Formatter)
+}