Migrating to the slnx format (#1591)

- `UnitsNet.sln` -> `UnitsNet.slnx` 
- `Samples/Samples.sln` -> `Samples/Samples.slnx`
- `Samples/MvvmSample.Wpf/MvvmSample.Wpf.sln` ->
`Samples/MvvmSample.Wpf/MvvmSample.Wpf.slnx`
- `Samples/UnitConverter.Wpf/UnitConverter.Wpf.sln` ->
`Samples/UnitConverter.Wpf/UnitConverter.Wpf.slnx`

and updating the build functions that reference `UnitsNet.sln`

Author: lipchev

Build/build-functions.psm1

@@ -36,7 +36,7 @@ function Start-Build([boolean] $IncludeNanoFramework = $false) {
 
   $fileLoggerArg = "/logger:FileLogger,Microsoft.Build;logfile=$logsDir\UnitsNet.msbuild.log"
 
-  dotnet build --configuration Release /p:ContinuousIntegrationBuild=true "$root\UnitsNet.sln" $fileLoggerArg
+  dotnet build --configuration Release /p:ContinuousIntegrationBuild=true "$root\UnitsNet.slnx" $fileLoggerArg
   if ($lastexitcode -ne 0) { exit 1 }
 
   if (-not $IncludeNanoFramework)

CodeGen/Program.cs

@@ -106,7 +106,7 @@ private static DirectoryInfo FindRepositoryRoot()
 
             for (var dir = executableParentDir; dir != null; dir = dir.Parent)
             {
-                if (dir.GetFiles("UnitsNet.sln").Any())
+                if (dir.GetFiles("UnitsNet.slnx").Any())
                 {
                     Log.Verbose("Found repo root: {Dir}", dir);
                     return dir;

Samples/MvvmSample.Wpf/MvvmSample.Wpf.sln

@@ -0,0 +1,3 @@
+<Solution>
+  <Project Path="MvvmSample.Wpf/MvvmSample.Wpf.csproj" />
+</Solution>

Samples/MvvmSample.Wpf/MvvmSample.Wpf.slnx

@@ -0,0 +1,20 @@
+<Solution>
+  <Configurations>
+    <Platform Name="Any CPU" />
+    <Platform Name="ARM" />
+    <Platform Name="x64" />
+    <Platform Name="x86" />
+  </Configurations>
+  <Folder Name="/_Files/">
+    <File Path="build.bat" />
+    <File Path="Directory.Packages.props" />
+    <File Path="msbuild.cmd" />
+  </Folder>
+  <Project Path="MvvmSample.Wpf/MvvmSample.Wpf/MvvmSample.Wpf.csproj">
+    <Build Solution="*|ARM" Project="false" />
+  </Project>
+  <Project Path="UnitConverter.Console/UnitConverter.Console.csproj" />
+  <Project Path="UnitConverter.Wpf/UnitConverter.Wpf/UnitConverter.Wpf.csproj">
+    <Build Solution="*|ARM" Project="false" />
+  </Project>
+</Solution>

Samples/Samples.sln

@@ -0,0 +1,3 @@
+<Solution>
+  <Project Path="UnitConverter.Wpf/UnitConverter.Wpf.csproj" />
+</Solution>