Fix all possible setting error related storages and added some tests (#23911)

Follow up #22405

Fix #20703 

This PR rewrites storage configuration read sequences with some breaks
and tests. It becomes more strict than before and also fixed some
inherit problems.

- Move storage's MinioConfig struct into setting, so after the
configuration loading, the values will be stored into the struct but not
still on some section.
- All storages configurations should be stored on one section,
configuration items cannot be overrided by multiple sections. The
prioioty of configuration is `[attachment]` > `[storage.attachments]` |
`[storage.customized]` > `[storage]` > `default`
- For extra override configuration items, currently are `SERVE_DIRECT`,
`MINIO_BASE_PATH`, `MINIO_BUCKET`, which could be configured in another
section. The prioioty of the override configuration is `[attachment]` >
`[storage.attachments]` > `default`.
- Add more tests for storages configurations.
- Update the storage documentations.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

cmd/migrate_storage.go

@@ -179,7 +179,7 @@ func runMigrateStorage(ctx *cli.Context) error {
 	switch strings.ToLower(ctx.String("storage")) {
 	case "":
 		fallthrough
-	case string(storage.LocalStorageType):
+	case string(setting.LocalStorageType):
 		p := ctx.String("path")
 		if p == "" {
 			log.Fatal("Path must be given when storage is loal")
@@ -187,22 +187,24 @@ func runMigrateStorage(ctx *cli.Context) error {
 		}
 		dstStorage, err = storage.NewLocalStorage(
 			stdCtx,
-			storage.LocalStorageConfig{
+			&setting.Storage{
 				Path: p,
 			})
-	case string(storage.MinioStorageType):
+	case string(setting.MinioStorageType):
 		dstStorage, err = storage.NewMinioStorage(
 			stdCtx,
-			storage.MinioStorageConfig{
-				Endpoint:           ctx.String("minio-endpoint"),
-				AccessKeyID:        ctx.String("minio-access-key-id"),
-				SecretAccessKey:    ctx.String("minio-secret-access-key"),
-				Bucket:             ctx.String("minio-bucket"),
-				Location:           ctx.String("minio-location"),
-				BasePath:           ctx.String("minio-base-path"),
-				UseSSL:             ctx.Bool("minio-use-ssl"),
-				InsecureSkipVerify: ctx.Bool("minio-insecure-skip-verify"),
-				ChecksumAlgorithm:  ctx.String("minio-checksum-algorithm"),
+			&setting.Storage{
+				MinioConfig: setting.MinioStorageConfig{
+					Endpoint:           ctx.String("minio-endpoint"),
+					AccessKeyID:        ctx.String("minio-access-key-id"),
+					SecretAccessKey:    ctx.String("minio-secret-access-key"),
+					Bucket:             ctx.String("minio-bucket"),
+					Location:           ctx.String("minio-location"),
+					BasePath:           ctx.String("minio-base-path"),
+					UseSSL:             ctx.Bool("minio-use-ssl"),
+					InsecureSkipVerify: ctx.Bool("minio-insecure-skip-verify"),
+					ChecksumAlgorithm:  ctx.String("minio-checksum-algorithm"),
+				},
 			})
 	default:
 		return fmt.Errorf("unsupported storage type: %s", ctx.String("storage"))