Formatter: format around safe cast operator as? (KT-32324)

#KT-32324 Fixed

idea/testData/formatter/SafeCast.after.kt

@@ -0,0 +1,3 @@
+fun main(a: Any) {
+    a as? String
+}

idea/testData/formatter/SafeCast.kt

@@ -0,0 +1,3 @@
+fun main(a: Any) {
+    a   as?String
+}