FIR IDE: make compile-time constant evaluator an object

because it doesn't have any states.

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/components/KtFirCompileTimeConstantProvider.kt

@@ -25,7 +25,7 @@ internal class KtFirCompileTimeConstantProvider(
     override fun evaluate(expression: KtExpression): KtConstantValue? = withValidityAssertion {
         when (val fir = expression.getOrBuildFir(firResolveState)) {
             is FirExpression -> {
-                FirCompileTimeConstantEvaluator().evaluate(fir)?.let { KtFirConstantValueConverter.toConstantValue(it) }
+                FirCompileTimeConstantEvaluator.evaluate(fir)?.let { KtFirConstantValueConverter.toConstantValue(it) }
                     ?: KtFirConstantValueConverter.toConstantValue(fir, firResolveState.rootModuleSession)
             }
             else -> throwUnexpectedFirElementError(fir, expression)

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/evaluate/FirCompileTimeConstantEvaluator.kt

@@ -26,7 +26,7 @@ import org.jetbrains.kotlin.types.ConstantValueKind
  * An evaluator that transform numeric operation, such as div, into compile-time constant iff involved operands, such as explicit receiver
  * and the argument, are compile-time constant as well.
  */
-internal class FirCompileTimeConstantEvaluator {
+internal object FirCompileTimeConstantEvaluator {
 
     // TODO: Handle boolean operators, const property loading, class reference, array, annotation values, etc.
     fun evaluate(expression: FirExpression): FirConstExpression<*>? =