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/repository_archive.go

@@ -0,0 +1,25 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import "fmt"
+
+var RepoArchive = struct {
+	Storage *Storage
+}{}
+
+func loadRepoArchiveFrom(rootCfg ConfigProvider) (err error) {
+	sec, _ := rootCfg.GetSection("repo-archive")
+	if sec == nil {
+		RepoArchive.Storage, err = getStorage(rootCfg, "repo-archive", "", nil)
+		return err
+	}
+
+	if err := sec.MapTo(&RepoArchive); err != nil {
+		return fmt.Errorf("mapto repoarchive failed: %v", err)
+	}
+
+	RepoArchive.Storage, err = getStorage(rootCfg, "repo-archive", "", sec)
+	return err
+}