JVM_IR: Optimize null checks.

Introduce lowering to remove null checks for primitive type
expressions and replace them with true/false. Side-effects
are preserved.

Generate ifnull/ifnonnull instructions for null checks instead
of materializing a null literal for an equality check.

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

@@ -15977,6 +15977,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
         }
 
+        @TestMetadata("primitiveCheckWithSideEffect.kt")
+        public void testPrimitiveCheckWithSideEffect() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/primitiveCheckWithSideEffect.kt");
+        }
+
         @TestMetadata("trivialInstanceOf.kt")
         public void testTrivialInstanceOf() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/trivialInstanceOf.kt");