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>

modules/setting/attachment.go

@@ -5,29 +5,31 @@ package setting
 
 // Attachment settings
 var Attachment = struct {
-	Storage
+	Storage      *Storage
 	AllowedTypes string
 	MaxSize      int64
 	MaxFiles     int
 	Enabled      bool
 }{
-	Storage: Storage{
-		ServeDirect: false,
-	},
-	AllowedTypes: "image/jpeg,image/png,application/zip,application/gzip",
+	Storage:      &Storage{},
+	AllowedTypes: ".csv,.docx,.fodg,.fodp,.fods,.fodt,.gif,.gz,.jpeg,.jpg,.log,.md,.mov,.mp4,.odf,.odg,.odp,.ods,.odt,.patch,.pdf,.png,.pptx,.svg,.tgz,.txt,.webm,.xls,.xlsx,.zip",
 	MaxSize:      4,
 	MaxFiles:     5,
 	Enabled:      true,
 }
 
-func loadAttachmentFrom(rootCfg ConfigProvider) {
-	sec := rootCfg.Section("attachment")
-	storageType := sec.Key("STORAGE_TYPE").MustString("")
-
-	Attachment.Storage = getStorage(rootCfg, "attachments", storageType, sec)
+func loadAttachmentFrom(rootCfg ConfigProvider) (err error) {
+	sec, _ := rootCfg.GetSection("attachment")
+	if sec == nil {
+		Attachment.Storage, err = getStorage(rootCfg, "attachments", "", nil)
+		return err
+	}
 
 	Attachment.AllowedTypes = sec.Key("ALLOWED_TYPES").MustString(".csv,.docx,.fodg,.fodp,.fods,.fodt,.gif,.gz,.jpeg,.jpg,.log,.md,.mov,.mp4,.odf,.odg,.odp,.ods,.odt,.patch,.pdf,.png,.pptx,.svg,.tgz,.txt,.webm,.xls,.xlsx,.zip")
 	Attachment.MaxSize = sec.Key("MAX_SIZE").MustInt64(4)
 	Attachment.MaxFiles = sec.Key("MAX_FILES").MustInt(5)
 	Attachment.Enabled = sec.Key("ENABLED").MustBool(true)
+
+	Attachment.Storage, err = getStorage(rootCfg, "attachments", "", sec)
+	return err
 }