fix🐛: embed the seed SQL so migrate works outside the repository root

The seed scripts were read from ./config/ only, so migrating an empty database
failed anywhere that directory was absent, such as a container holding just
the binary and its settings. Embed them and prefer a file on disk when there
is one.

cmd/migrate/migration/models/initdb.go

@@ -3,7 +3,7 @@ package models
 import (
 	"fmt"
 	"go-admin/common/global"
-	"io/ioutil"
+	"go-admin/config"
 	"log"
 	"strings"
 
@@ -61,7 +61,7 @@ func ExecSql(db *gorm.DB, filePath string) error {
 }
 
 func Ioutil(filePath string) (string, error) {
-	if contents, err := ioutil.ReadFile(filePath); err == nil {
+	if contents, err := config.ReadSeed(filePath); err == nil {
 		//因为contents是[]byte类型，直接转换成string类型后会多一行空格,需要使用strings.Replace替换换行符
 		result := strings.Replace(string(contents), "\n", "", 1)
 		fmt.Println("Use ioutil.ReadFile to read a file:", result)