添加前端项目到解决方案（solution folder结构）

- src/frontend 作为 solution folder
- src/frontend/admin 作为 solution folder
- src/frontend/dashboard 作为 solution folder
- 在Visual Studio中显示为可折叠的文件夹结构

Haoliang.sln

@@ -11,6 +11,16 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Haoliang.Data", "Haoliang.D
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Haoliang.Models", "Haoliang.Models\Haoliang.Models.csproj", "{76F38B67-BFE3-4BCA-9447-0CCE85320CCE}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Haoliang.Tests", "Haoliang.Tests\Haoliang.Tests.csproj", "{96C52F85-18C9-4E62-B34C-F59551E8A67E}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{11111111-1111-1111-1111-111111111111}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "frontend", "src\frontend", "{22222222-2222-2222-2222-222222222222}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "admin", "src\frontend\admin", "{33333333-3333-3333-3333-333333333333}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "dashboard", "src\frontend\dashboard", "{44444444-4444-4444-4444-444444444444}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -36,5 +46,14 @@ Global
 		{76F38B67-BFE3-4BCA-9447-0CCE85320CCE}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{76F38B67-BFE3-4BCA-9447-0CCE85320CCE}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{76F38B67-BFE3-4BCA-9447-0CCE85320CCE}.Release|Any CPU.Build.0 = Release|Any CPU
+		{96C52F85-18C9-4E62-B34C-F59551E8A67E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{96C52F85-18C9-4E62-B34C-F59551E8A67E}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{96C52F85-18C9-4E62-B34C-F59551E8A67E}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{96C52F85-18C9-4E62-B34C-F59551E8A67E}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(NestedProjects) = preSolution
+		{22222222-2222-2222-2222-222222222222} = {11111111-1111-1111-1111-111111111111}
+		{33333333-3333-3333-3333-333333333333} = {22222222-2222-2222-2222-222222222222}
+		{44444444-4444-4444-4444-444444444444} = {22222222-2222-2222-2222-222222222222}
 	EndGlobalSection
-EndGlobal
+EndGlobal