CompilerArgumentsSerializerV5.serializeTo: fix NPE

NPE was happening on `?.takeIf { it.get(arguments) != it.get(newInstance) }` line.
It was happening because `it.get` could return `null`.

But the problem was only reproducible on TeamCity and not reproducible locally.

Test example (IJ repo): `org.jetbrains.kotlin.idea.fir.completion.HighLevelJvmBasicCompletionTestGenerated$Common$FromSmart.testArrayLiteralAnnotationConstructorAsDefaultValueForArray`
stacktrace:
```
java.lang.NullPointerException
  at org.jetbrains.kotlin.arguments.CompilerArgumentsSerializerV5.serializeTo(CompilerArgumentsSerializer.kt:23)
  at org.jetbrains.kotlin.config.FacetSerializationKt.writeLatestConfig(facetSerialization.kt:379)
  at org.jetbrains.kotlin.config.FacetSerializationKt.serializeFacetSettings(facetSerialization.kt:422)
  at org.jetbrains.kotlin.idea.facet.KotlinFacetConfigurationImpl.writeExternal(KotlinFacetConfigurationImpl.kt:24)
```

jps/jps-common/src/org/jetbrains/kotlin/arguments/CompilerArgumentsSerializer.kt

@@ -19,7 +19,7 @@ class CompilerArgumentsSerializerV5<T : CommonToolArguments>(override val argume
         val newInstance = arguments::class.java.getConstructor().newInstance()
         val flagArgumentsByName = CompilerArgumentsContentProspector.getFlagCompilerArgumentProperties(arguments::class)
             .mapNotNull { prop ->
-                prop.safeAs<KProperty1<T, Boolean>>()
+                prop.safeAs<KProperty1<T, Boolean?>>()
                     ?.takeIf { it.get(arguments) != it.get(newInstance) }
                     ?.get(arguments)
                     ?.let { prop.name to it }