Add local dev convenience scripts (dotnet#3389)

Author: RussKie

build-local.ps1

@@ -0,0 +1,29 @@
+@ECHO OFF
+SETLOCAL
+
+:: This command launches a Visual Studio Code with environment variables required to use a local version of the .NET Core SDK.
+
+FOR /f "delims=" %%a IN ('where.exe code') DO @SET vscode=%%a& GOTO break
+:break
+
+IF ["%vscode%"] == [""] (
+    echo [ERROR] Visual Studio Code is not installed or can't be found.
+    exit /b 1
+)
+
+:: This tells .NET Core to use the same dotnet.exe that build scripts use
+SET DOTNET_ROOT=%~dp0.dotnet
+SET DOTNET_ROOT(x86)=%~dp0.dotnet\x86
+
+:: This tells .NET Core not to go looking for .NET Core in other places
+SET DOTNET_MULTILEVEL_LOOKUP=0
+
+:: Put our local dotnet.exe on PATH first so Visual Studio knows which one to use
+SET PATH=%DOTNET_ROOT%;%PATH%
+
+IF NOT EXIST "%DOTNET_ROOT%\dotnet.exe" (
+    echo [ERROR] .NET has not yet been installed. Run `%~dp0restore.cmd` to install tools
+    exit /b 1
+)
+
+"%vscode%" "."

start-code.cmd

@@ -0,0 +1,21 @@
+@ECHO OFF
+SETLOCAL
+
+:: This command launches a Visual Studio solution with environment variables required to use a local version of the .NET Core SDK.
+
+:: This tells .NET Core to use the same dotnet.exe that build scripts use
+SET DOTNET_ROOT=%~dp0.dotnet
+SET DOTNET_ROOT(x86)=%~dp0.dotnet\x86
+
+:: This tells .NET Core not to go looking for .NET Core in other places
+SET DOTNET_MULTILEVEL_LOOKUP=0
+
+:: Put our local dotnet.exe on PATH first so Visual Studio knows which one to use
+SET PATH=%DOTNET_ROOT%;%PATH%
+
+IF NOT EXIST "%DOTNET_ROOT%\dotnet.exe" (
+    echo [ERROR] .NET Core has not yet been installed. Run `%~dp0restore.cmd` to install tools
+    exit /b 1
+)
+
+start "" "Winforms.sln"