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/storage/local.go

@@ -12,20 +12,12 @@ import (
 	"path/filepath"
 
 	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
 )
 
 var _ ObjectStorage = &LocalStorage{}
 
-// LocalStorageType is the type descriptor for local storage
-const LocalStorageType Type = "local"
-
-// LocalStorageConfig represents the configuration for a local storage
-type LocalStorageConfig struct {
-	Path          string `ini:"PATH"`
-	TemporaryPath string `ini:"TEMPORARY_PATH"`
-}
-
 // LocalStorage represents a local files storage
 type LocalStorage struct {
 	ctx    context.Context
@@ -34,13 +26,7 @@ type LocalStorage struct {
 }
 
 // NewLocalStorage returns a local files
-func NewLocalStorage(ctx context.Context, cfg interface{}) (ObjectStorage, error) {
-	configInterface, err := toConfig(LocalStorageConfig{}, cfg)
-	if err != nil {
-		return nil, err
-	}
-	config := configInterface.(LocalStorageConfig)
-
+func NewLocalStorage(ctx context.Context, config *setting.Storage) (ObjectStorage, error) {
 	if !filepath.IsAbs(config.Path) {
 		return nil, fmt.Errorf("LocalStorageConfig.Path should have been prepared by setting/storage.go and should be an absolute path, but not: %q", config.Path)
 	}
@@ -164,5 +150,5 @@ func (l *LocalStorage) IterateObjects(dirName string, fn func(path string, obj O
 }
 
 func init() {
-	RegisterStorageType(LocalStorageType, NewLocalStorage)
+	RegisterStorageType(setting.LocalStorageType, NewLocalStorage)
 }