Azure blob storage support (#30995)

This PR implemented object storages(LFS/Packages/Attachments and etc.)
for Azure Blob Storage. It depends on azure official golang SDK and can
support both the azure blob storage cloud service and azurite mock
server.

Replace #25458
Fix #22527 

- [x] CI Tests
- [x] integration test, MSSQL integration tests will now based on
azureblob
  - [x] unit test 
- [x] CLI Migrate Storage
- [x] Documentation for configuration added

------

TODO (other PRs):
- [ ] Improve performance of `blob download`.

---------

Co-authored-by: yp05327 <576951401@qq.com>

modules/storage/azureblob_test.go

@@ -0,0 +1,56 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package storage
+
+import (
+	"os"
+	"testing"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAzureBlobStorageIterator(t *testing.T) {
+	if os.Getenv("CI") == "" {
+		t.Skip("azureBlobStorage not present outside of CI")
+		return
+	}
+	testStorageIterator(t, setting.AzureBlobStorageType, &setting.Storage{
+		AzureBlobConfig: setting.AzureBlobStorageConfig{
+			// https://learn.microsoft.com/azure/storage/common/storage-use-azurite?tabs=visual-studio-code#ip-style-url
+			Endpoint: "http://devstoreaccount1.azurite.local:10000",
+			// https://learn.microsoft.com/azure/storage/common/storage-use-azurite?tabs=visual-studio-code#well-known-storage-account-and-key
+			AccountName: "devstoreaccount1",
+			AccountKey:  "Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==",
+			Container:   "test",
+		},
+	})
+}
+
+func TestAzureBlobStoragePath(t *testing.T) {
+	m := &AzureBlobStorage{cfg: &setting.AzureBlobStorageConfig{BasePath: ""}}
+	assert.Equal(t, "", m.buildAzureBlobPath("/"))
+	assert.Equal(t, "", m.buildAzureBlobPath("."))
+	assert.Equal(t, "a", m.buildAzureBlobPath("/a"))
+	assert.Equal(t, "a/b", m.buildAzureBlobPath("/a/b/"))
+
+	m = &AzureBlobStorage{cfg: &setting.AzureBlobStorageConfig{BasePath: "/"}}
+	assert.Equal(t, "", m.buildAzureBlobPath("/"))
+	assert.Equal(t, "", m.buildAzureBlobPath("."))
+	assert.Equal(t, "a", m.buildAzureBlobPath("/a"))
+	assert.Equal(t, "a/b", m.buildAzureBlobPath("/a/b/"))
+
+	m = &AzureBlobStorage{cfg: &setting.AzureBlobStorageConfig{BasePath: "/base"}}
+	assert.Equal(t, "base", m.buildAzureBlobPath("/"))
+	assert.Equal(t, "base", m.buildAzureBlobPath("."))
+	assert.Equal(t, "base/a", m.buildAzureBlobPath("/a"))
+	assert.Equal(t, "base/a/b", m.buildAzureBlobPath("/a/b/"))
+
+	m = &AzureBlobStorage{cfg: &setting.AzureBlobStorageConfig{BasePath: "/base/"}}
+	assert.Equal(t, "base", m.buildAzureBlobPath("/"))
+	assert.Equal(t, "base", m.buildAzureBlobPath("."))
+	assert.Equal(t, "base/a", m.buildAzureBlobPath("/a"))
+	assert.Equal(t, "base/a/b", m.buildAzureBlobPath("/a/b/"))
+}