refactor(converters): Improve name detection

Some workout files don't have a name; in that case, we use the filename
as the name of the workout.

pkg/converters/parse.go

@@ -16,6 +16,21 @@ func Parse(filename string, content []byte) (*gpx.GPX, error) {
 		return ParseGPX(content)
 	}
 
+	basename := path.Base(filename)
+
+	c, err := parseContent(basename, content)
+	if err != nil {
+		return nil, err
+	}
+
+	if c.Name == "" {
+		c.Name = basename
+	}
+
+	return c, nil
+}
+
+func parseContent(filename string, content []byte) (*gpx.GPX, error) {
 	suffix := path.Ext(filename)
 
 	switch suffix {