logger: add caller info to default implementation (#1575)

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

logger/options.go

@@ -14,6 +14,8 @@ type Options struct {
 	Fields map[string]interface{}
 	// It's common to set this to a file, or leave it default which is `os.Stderr`
 	Out io.Writer
+	// Caller skip frame count for file:line info
+	CallerSkipCount int
 	// Alternative options
 	Context context.Context
 }
@@ -39,6 +41,13 @@ func WithOutput(out io.Writer) Option {
 	}
 }
 
+// WithCallerSkipCount set frame count to skip
+func WithCallerSkipCount(c int) Option {
+	return func(args *Options) {
+		args.CallerSkipCount = c
+	}
+}
+
 func SetOption(k, v interface{}) Option {
 	return func(o *Options) {
 		if o.Context == nil {