Add smol caching & a utility method

[pyricau]

No description provided.

[zach-klippenstein]

FYI: Each by lazy allocates an additional private object to store the property delegate. If we don't need multi-thread synchronization, it's cheaper to just use a nullable backing property and initialize it yourself. Usually matters more for framework code, so we might want to avoid by lazy here.

E.g.

private var _cachedToString: String?
private val cachedToString: String
  get() = _cachedToString ?: calculateToString().also { _cachedToString = it }

[pyricau]

Did that but made cachedToString volatile because I'm not 100% this is actually single threaded. volatile is still better than using synchronization primitives as there's no locking, and the downside is that we might sometimes race init and compute it twice then set it twice to the same value, which is ok.

[steve-the-edwards]

See build failure - we run in explicit API mode, so you need to add return types explicitly.

[steve-the-edwards]

This is what needs an explicit type declared.

[pyricau]

e: file:///home/runner/work/workflow-kotlin/workflow-kotlin/workflow-core/src/commonMain/kotlin/com/squareup/workflow1/WorkflowIdentifier.kt:69:57 Platform declaration clash: The following declarations have the same JVM signature (getRealIdentifierType()Lcom/squareup/workflow1/WorkflowIdentifierType;):
    fun `<get-realIdentifierType>`(): WorkflowIdentifierType defined in com.squareup.workflow1.WorkflowIdentifier
    fun getRealIdentifierType(): WorkflowIdentifierType defined in com.squareup.workflow1.WorkflowIdentifier

I was surprised that the IDE was fine with it.

[pyricau]

To avoid the conflict, renamed the field to realType which is better anyway