Usings
Controls whether Curb sorts System.* directives before all others, inserts blank lines between using groups, and moves using directives inside or outside the namespace declaration. IDE0065.
csharp_using_directive_placement
Move using directives inside or outside the namespace. IDE0065. Defaults to `(as written)`
dotnet_separate_import_directive_groups
Separate groups of usings by first namespace segment with a blank line. Defaults to `false`
dotnet_sort_system_directives_first
Put System.* usings before all others. Defaults to `false`