Add settings for .NET Download timeout (#991)

When you in remote area, inability to specify download timeout cause problems

By default set to 20 minutes which is default for dotnet-install.ps1

src/build.cmd

@@ -10,28 +10,29 @@ rem Install required .NET SDK version and add to environment
 set DOTNET_ROOT=%LocalAppData%\Microsoft\dotnet
 set DOTNET_ROOT(86)=%LocalAppData%\Microsoft\dotnet\x86
 set path=%DOTNET_ROOT%;%path%
+set DownloadTimeout=1200
 
 rem Install .net5 to run our projects  targeting it
 powershell -NoProfile -ExecutionPolicy unrestricted -Command ^
 [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; ^
 &([scriptblock]::Create((Invoke-WebRequest -UseBasicParsing 'https://dot.net/v1/dotnet-install.ps1'))) ^
--Version '%CsWinRTNet5SdkVersion%' -InstallDir '%DOTNET_ROOT%' -Architecture 'x64' ^
+-Version '%CsWinRTNet5SdkVersion%' -InstallDir '%DOTNET_ROOT%' -Architecture 'x64' -DownloadTimeout %DownloadTimeout% ^
 -AzureFeed 'https://dotnetcli.blob.core.windows.net/dotnet'
 powershell -NoProfile -ExecutionPolicy unrestricted -Command ^
 [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; ^
 &([scriptblock]::Create((Invoke-WebRequest -UseBasicParsing 'https://dot.net/v1/dotnet-install.ps1'))) ^
--Version '%CsWinRTNet5SdkVersion%' -InstallDir '%DOTNET_ROOT(86)%' -Architecture 'x86' ^
+-Version '%CsWinRTNet5SdkVersion%' -InstallDir '%DOTNET_ROOT(86)%' -Architecture 'x86' -DownloadTimeout %DownloadTimeout% ^
 -AzureFeed 'https://dotnetcli.blob.core.windows.net/dotnet'
 rem Install .NET Version used to build projection
 powershell -NoProfile -ExecutionPolicy unrestricted -Command ^
 [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; ^
 &([scriptblock]::Create((Invoke-WebRequest -UseBasicParsing 'https://dot.net/v1/dotnet-install.ps1'))) ^
--Version '%CsWinRTBuildNetSDKVersion%' -InstallDir '%DOTNET_ROOT%' -Architecture 'x64' ^
+-Version '%CsWinRTBuildNetSDKVersion%' -InstallDir '%DOTNET_ROOT%' -Architecture 'x64' -DownloadTimeout %DownloadTimeout% ^
 -AzureFeed 'https://dotnetcli.blob.core.windows.net/dotnet'
 powershell -NoProfile -ExecutionPolicy unrestricted -Command ^
 [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; ^
 &([scriptblock]::Create((Invoke-WebRequest -UseBasicParsing 'https://dot.net/v1/dotnet-install.ps1'))) ^
--Version '%CsWinRTBuildNetSDKVersion%' -InstallDir '%DOTNET_ROOT(86)%' -Architecture 'x86' ^
+-Version '%CsWinRTBuildNetSDKVersion%' -InstallDir '%DOTNET_ROOT(86)%' -Architecture 'x86' -DownloadTimeout %DownloadTimeout% ^
 -AzureFeed 'https://dotnetcli.blob.core.windows.net/dotnet'
 
 :globaljson