KT-14227 Intrinsify MutableMap.set

This fixes the most common (and rather annoying) bug in augmented
assignment desugaring with collection element receiver.

Fix is somewhat hackish: introduce an intrinsic for MutableMap.set,
thus bypassing discrepancies in 'get' and 'set' call generation.
Fixing it properly requires design decisions for corner cases where
ad hoc augmented assignment desugaring with collection element receiver
"accidentally" works, producing identical objects and vararg arrays for
arguments of 'get' and 'set'.

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -16394,6 +16394,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/operatorConventions/kt14201_2.kt");
         }
 
+        @TestMetadata("kt14227.kt")
+        public void testKt14227() throws Exception {
+            runTest("compiler/testData/codegen/box/operatorConventions/kt14227.kt");
+        }
+
         @TestMetadata("kt20387.kt")
         public void testKt20387() throws Exception {
             runTest("compiler/testData/codegen/box/operatorConventions/kt20387.kt");