FIR: Fix operator and infix flags for FIR builtins

compiler/testData/ir/irText/expressions/builtinOperators.kt.txt

@@ -0,0 +1,9 @@
+package test
+
+fun callBuiltinFunctions(a: Int, b: Int) {
+  a.plus(other = b) /*~> Unit */
+  a.or(other = b) /*~> Unit */
+  a.and(other = b) /*~> Unit */
+  a.inv() /*~> Unit */
+  a.shl(bitCount = b) /*~> Unit */
+}