Currently the files in the solution folder, such as Directory.Build.props, Directory.Packages.props, and others, are not formatted during msbuild.
We also have custom XMLs in the root folder, which would be good to have formatted with CSharpier.

Environments:

• CSharpier Version: 1.2.1
• Running CSharpier via: msbuild
• Operating System: Windows/Linux
• .csharpierrc Settings: -
• .editorconfig Settings:

indent_style = tab
indent_size = 4

Steps to reproduce:
Add:

    <GlobalPackageReference Include="CSharpier.MSBuild" PrivateAssets="all" Version="1.2.1" />

to Directory.Packages.props.
Run dotnet build or build via an IDE.
Expected behavior:
Directory.Packages.props and other files in the root directory, containing .sln are formatted.
Actual behavior:
Directory.Packages.props and other files in the root directory, containing .sln are not formatted.