Merge pull request #3012 from tomerd/swiftformat

add swiftformat config file

Author: abertelrud

.swiftformat

@@ -0,0 +1,13 @@
+# file options
+
+--swiftversion 5.0
+--exclude .build
+
+# format options
+
+--self insert
+--patternlet inline
+--stripunusedargs unnamed-only
+--ifdef no-indent
+
+# rules