feat: give Visual Studio icon to Solution Filter files (#3272)

Signed-off-by: Firecrafter28 <74384569+Firecrafter28@users.noreply.github.com>
Co-authored-by: Philipp Kief <philipp.kief@gmx.de>

Author: Firecrafter28

src/core/icons/fileIcons.ts

@@ -384,6 +384,7 @@ export const fileIcons: FileIcons = {
         'csproj',
         'ruleset',
         'sln',
+        'slnf',
         'slnx',
         'suo',
         'vb',