Use MSBuild properties to update solution file name and enable folder creation

[mruxmohan4]

As discussed in #503, use the SlnGenFolders and SlnGenProjectName MSBuild properties to customize solution file names and enable folder creation in solutions.

This avoids the need for developers to both a) type --folder true and b) use the default dirs.proj (which appears in VS solution explorer as well):

Build started 11/15/2023 7:12:30 PM.
Searching "C:\src\test\slngen-custom\Custom" for projects
Generating solution for project "C:\src\test\slngen-custom\Custom\dirs.proj"
Loading project references...
Loaded 1 project(s) in 971ms
Generating Visual Studio solution "C:\src\test\slngen-custom\Custom\MyAwesomeComponent.sln" ...
Launching Visual Studio...

Success
    0 Warning(s)
    0 Error(s)

Example dirs.proj with the properties set:

<Project Sdk="Microsoft.Build.Traversal">
  <PropertyGroup>
    <SlnGenFolders>true</SlnGenFolders>
    <SlnGenProjectName>MyAwesomeComponent</SlnGenProjectName>
  </PropertyGroup>
  <ItemGroup>
    <!-- Build all projects recursively -->
    <ProjectReference Include="**/*.*proj" />
  </ItemGroup>
</Project>