[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/testData/diagnostics/testsWithStdLib/enumEntryInitialization.kt

@@ -25,4 +25,19 @@ enum class JvmTarget(val description: String) {
             JVM_15 -> "Opcodes.V12 + 3"
         }
     }
+
+    // Should not report UNINITIALIZED_ENUM_ENTRY
+    val bytecodeVersion2: String by lazy({
+        when (this) {
+            JVM_1_6 -> "Opcodes.V1_6"
+            JVM_1_8 -> "Opcodes.V1_8"
+            JVM_9 -> "Opcodes.V9"
+            JVM_10 -> "Opcodes.V10"
+            JVM_11 -> "Opcodes.V11"
+            JVM_12 -> "Opcodes.V12"
+            JVM_13 -> "Opcodes.V12 + 1"
+            JVM_14 -> "Opcodes.V12 + 2"
+            JVM_15 -> "Opcodes.V12 + 3"
+        }
+    })
 }