Restructure project directories

Follow the standard of all go projects

internal/config/errors.go

@@ -0,0 +1,25 @@
+package config
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+const (
+	errNoCommand             = "at least one command must be specified, use help to get commands"
+	errNotSupportedType      = "not supported configuration type"
+	errMissingWorkspaceField = "missing required \"workspace\" field"
+	errMissingSrcField       = "missing required field the \"src\" in row %v"
+	errNameAndTagsTogether   = "name and tags arguments connot be used together"
+)
+
+func getDuplicateFieldError(field string, name string, rows []int) error {
+
+	var rowsInString []string
+	for _, row := range rows {
+		rowsInString = append(rowsInString, strconv.Itoa(row))
+	}
+
+	return fmt.Errorf("the %v \"%v\" is duplicated in rows: %v", field, name, strings.Join(rowsInString, ","))
+}