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_test.go

@@ -0,0 +1,133 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_getStorageCustomType(t *testing.T) {
+	iniStr := `
+[attachment]
+STORAGE_TYPE = my_minio
+MINIO_BUCKET = gitea-attachment
+
+[storage.my_minio]
+STORAGE_TYPE = minio
+MINIO_ENDPOINT = my_minio:9000
+`
+	cfg, err := NewConfigProviderFromData(iniStr)
+	assert.NoError(t, err)
+
+	assert.NoError(t, loadAttachmentFrom(cfg))
+
+	assert.EqualValues(t, "minio", Attachment.Storage.Type)
+	assert.EqualValues(t, "my_minio:9000", Attachment.Storage.MinioConfig.Endpoint)
+	assert.EqualValues(t, "gitea-attachment", Attachment.Storage.MinioConfig.Bucket)
+	assert.EqualValues(t, "attachments/", Attachment.Storage.MinioConfig.BasePath)
+}
+
+func Test_getStorageTypeSectionOverridesStorageSection(t *testing.T) {
+	iniStr := `
+[attachment]
+STORAGE_TYPE = minio
+
+[storage.minio]
+MINIO_BUCKET = gitea-minio
+
+[storage]
+MINIO_BUCKET = gitea
+`
+	cfg, err := NewConfigProviderFromData(iniStr)
+	assert.NoError(t, err)
+
+	assert.NoError(t, loadAttachmentFrom(cfg))
+
+	assert.EqualValues(t, "minio", Attachment.Storage.Type)
+	assert.EqualValues(t, "gitea-minio", Attachment.Storage.MinioConfig.Bucket)
+	assert.EqualValues(t, "attachments/", Attachment.Storage.MinioConfig.BasePath)
+}
+
+func Test_getStorageSpecificOverridesStorage(t *testing.T) {
+	iniStr := `
+[attachment]
+STORAGE_TYPE = minio
+MINIO_BUCKET = gitea-attachment
+
+[storage.attachments]
+MINIO_BUCKET = gitea
+
+[storage]
+STORAGE_TYPE = local
+`
+	cfg, err := NewConfigProviderFromData(iniStr)
+	assert.NoError(t, err)
+
+	assert.NoError(t, loadAttachmentFrom(cfg))
+
+	assert.EqualValues(t, "minio", Attachment.Storage.Type)
+	assert.EqualValues(t, "gitea-attachment", Attachment.Storage.MinioConfig.Bucket)
+	assert.EqualValues(t, "attachments/", Attachment.Storage.MinioConfig.BasePath)
+}
+
+func Test_getStorageGetDefaults(t *testing.T) {
+	cfg, err := NewConfigProviderFromData("")
+	assert.NoError(t, err)
+
+	assert.NoError(t, loadAttachmentFrom(cfg))
+
+	// default storage is local, so bucket is empty
+	assert.EqualValues(t, "", Attachment.Storage.MinioConfig.Bucket)
+}
+
+func Test_getStorageInheritNameSectionType(t *testing.T) {
+	iniStr := `
+[storage.attachments]
+STORAGE_TYPE = minio
+`
+	cfg, err := NewConfigProviderFromData(iniStr)
+	assert.NoError(t, err)
+
+	assert.NoError(t, loadAttachmentFrom(cfg))
+
+	assert.EqualValues(t, "minio", Attachment.Storage.Type)
+}
+
+func Test_AttachmentStorage(t *testing.T) {
+	iniStr := `
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+[storage]
+STORAGE_TYPE            = minio
+MINIO_ENDPOINT          = s3.my-domain.net
+MINIO_BUCKET            = gitea
+MINIO_LOCATION          = homenet
+MINIO_USE_SSL           = true
+MINIO_ACCESS_KEY_ID     = correct_key
+MINIO_SECRET_ACCESS_KEY = correct_key
+`
+	cfg, err := NewConfigProviderFromData(iniStr)
+	assert.NoError(t, err)
+
+	assert.NoError(t, loadAttachmentFrom(cfg))
+	storage := Attachment.Storage
+
+	assert.EqualValues(t, "minio", storage.Type)
+	assert.EqualValues(t, "gitea", storage.MinioConfig.Bucket)
+}
+
+func Test_AttachmentStorage1(t *testing.T) {
+	iniStr := `
+[storage]
+STORAGE_TYPE = minio
+`
+	cfg, err := NewConfigProviderFromData(iniStr)
+	assert.NoError(t, err)
+
+	assert.NoError(t, loadAttachmentFrom(cfg))
+	assert.EqualValues(t, "minio", Attachment.Storage.Type)
+	assert.EqualValues(t, "gitea", Attachment.Storage.MinioConfig.Bucket)
+	assert.EqualValues(t, "attachments/", Attachment.Storage.MinioConfig.BasePath)
+}