Replace MSBuild.Dev.sln and MSBuild.SourceBuild.sln with solution fil…

…ters (#6010)

Trivially replaced the two .sln's, which are a strict subset of MSBuild.sln, with .slnf's for easier maintenance.

MSBuild.Dev.slnf

@@ -0,0 +1,19 @@
+{
+  "solution": {
+    "path": "MSBuild.sln",
+    "projects": [
+      "src\\Build.OM.UnitTests\\Microsoft.Build.Engine.OM.UnitTests.csproj",
+      "src\\Build.UnitTests\\Microsoft.Build.Engine.UnitTests.csproj",
+      "src\\Build\\Microsoft.Build.csproj",
+      "src\\Framework.UnitTests\\Microsoft.Build.Framework.UnitTests.csproj",
+      "src\\Framework\\Microsoft.Build.Framework.csproj",
+      "src\\MSBuild.UnitTests\\Microsoft.Build.CommandLine.UnitTests.csproj",
+      "src\\MSBuild\\MSBuild.csproj",
+      "src\\Tasks.UnitTests\\Microsoft.Build.Tasks.UnitTests.csproj",
+      "src\\Tasks\\Microsoft.Build.Tasks.csproj",
+      "src\\Utilities.UnitTests\\Microsoft.Build.Utilities.UnitTests.csproj",
+      "src\\Utilities\\Microsoft.Build.Utilities.csproj",
+      "src\\Xunit.NetCore.Extensions\\Xunit.NetCore.Extensions.csproj"
+    ]
+  }
+}

MSBuild.SourceBuild.slnf

@@ -0,0 +1,13 @@
+{
+  "solution": {
+    "path": "MSBuild.sln",
+    "projects": [
+      "src\\Build\\Microsoft.Build.csproj",
+      "src\\Framework\\Microsoft.Build.Framework.csproj",
+      "src\\MSBuild\\MSBuild.csproj",
+      "src\\Package\\Localization\\Localization.csproj",
+      "src\\Tasks\\Microsoft.Build.Tasks.csproj",
+      "src\\Utilities\\Microsoft.Build.Utilities.csproj"
+    ]
+  }
+}

README.md

@@ -43,7 +43,7 @@ To get started on **Visual Studio 2019**:
 3. Clone the source code: `git clone https://github.com/Microsoft/msbuild.git`
   - You may have to [download Git](https://git-scm.com/downloads) first.
 4. Run `.\build.cmd` from the root of the repo to build the code. This also restores packages needed to open the projects in Visual Studio.
-5. Open `MSBuild.sln` or `MSBuild.Dev.sln` in Visual Studio 2019.
+5. Open `MSBuild.sln` or `MSBuild.Dev.slnf` in Visual Studio 2019.
 
 Note: To create a usable MSBuild with your changes, run `.\build.cmd /p:CreateBootstrap=true`.