[FIR] Remove FirLambdaArgumentExpression

It's not really necessary if the information about if the lambda was a
trailing lambda can be directly saved in FirAnonymousFunctionExpression.

Removing the FIR node uncovered a couple of bugs
(UNINITIALIZED_ENUM_ENTRY, ERROR_IN_CONTRACT_DESCRIPTION) that were
caused by assuming that a lambda is always a trailing lambda.

#KT-66124

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/FirArgumentsToParametersMapper.kt

@@ -75,7 +75,7 @@ fun BodyResolveComponents.mapArguments(
     val excessLambdaArguments: MutableList<FirExpression> = mutableListOf()
     var externalArgument: FirExpression? = null
     for (argument in arguments) {
-        if (argument is FirLambdaArgumentExpression) {
+        if (argument is FirAnonymousFunctionExpression && argument.isTrailingLambda) {
             if (externalArgument == null) {
                 externalArgument = argument
             } else {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirCallCompleter.kt

@@ -298,7 +298,7 @@ class FirCallCompleter(
 
             val matchedParameter = candidate.argumentMapping?.firstNotNullOfOrNull { (currentArgument, currentValueParameter) ->
                 val currentLambdaArgument =
-                    ((currentArgument as? FirLambdaArgumentExpression)?.expression as? FirAnonymousFunctionExpression)?.anonymousFunction
+                    (currentArgument as? FirAnonymousFunctionExpression)?.anonymousFunction
                 if (currentLambdaArgument === lambdaArgument) {
                     currentValueParameter
                 } else {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/contracts/FirAbstractContractResolveTransformerDispatcher.kt

@@ -170,10 +170,10 @@ abstract class FirAbstractContractResolveTransformerDispatcher(
                 owner.body.replaceFirstStatement<FirContractCallBlock> { FirContractCallBlock(resolvedContractCall) }
             }
 
-            val argument = resolvedContractCall.arguments.singleOrNull() as? FirLambdaArgumentExpression
+            val argument = resolvedContractCall.arguments.singleOrNull() as? FirAnonymousFunctionExpression
                 ?: return transformOwnerOfErrorContract(owner)
 
-            val lambdaBody = (argument.expression as FirAnonymousFunctionExpression).anonymousFunction.body
+            val lambdaBody = argument.anonymousFunction.body
                 ?: return transformOwnerOfErrorContract(owner)
 
             val resolvedContractDescription = buildResolvedContractDescription {
@@ -227,10 +227,9 @@ abstract class FirAbstractContractResolveTransformerDispatcher(
                 }
             }
 
-            val lambdaArgument = buildLambdaArgumentExpression {
-                expression = buildAnonymousFunctionExpression {
-                    anonymousFunction = effectsBlock
-                }
+            val lambdaArgument = buildAnonymousFunctionExpression {
+                anonymousFunction = effectsBlock
+                isTrailingLambda = true
             }
 
             val contractCall = buildFunctionCall {