Fix array access expression getKtType() bug

For an array access expression e.g., `foo[3]`,
KtFirExpressionTypeProvider first tries
`getReturnTypeForArrayStyleAssignmentTarget(..)` method that determines
the type of the array access expression when it is in the form of "set"
the value. However, the method also returns a non-null result for an
array access expression that reads its value i.e., "get". In this case,
the result of `getKtType()` becomes wrong. This commit lets the method
return a null for the type of "get" array access expression.

analysis/analysis-api-standalone/tests-gen/org/jetbrains/kotlin/analysis/api/standalone/fir/test/cases/generated/cases/components/expressionTypeProvider/FirStandaloneNormalAnalysisSourceModuleHLExpressionTypeTestGenerated.java

@@ -258,5 +258,11 @@ public class FirStandaloneNormalAnalysisSourceModuleHLExpressionTypeTestGenerate
         public void testArrayCompoundAssignementTarget() throws Exception {
             runTest("analysis/analysis-api/testData/components/expressionTypeProvider/expressionType/assignment/arrayCompoundAssignementTarget.kt");
         }
+
+        @Test
+        @TestMetadata("readArrayElement.kt")
+        public void testReadArrayElement() throws Exception {
+            runTest("analysis/analysis-api/testData/components/expressionTypeProvider/expressionType/assignment/readArrayElement.kt");
+        }
     }
 }