Add spacing option for spread operator (`..`)

Currently I'm using `csharp_space_around_binary_operators` (currently set to `before_and_after` in .editorconfig And it seems spread operator (`..`) is counted as a binary operator. So I'd like an option to control the spacing option specifically for spread operator as I'd generally would like to keep `before_and_after` but I prefer this style for the spread operator `..listA, ..listB` For now I'm either forced to disable the option in editorconfig or no warn for the formatting issue. Unsure which category is correct for this one so I chose blank.