[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/tests-spec/testData/diagnostics/notLinked/contracts/declarations/contractBuilder/common/neg/12.fir.kt

@@ -29,7 +29,7 @@ import kotlin.contracts.*
 
 // TESTCASE NUMBER: 1
 inline fun case_1(block: () -> Unit) {
-    contract(builder = { callsInPlaceEffectBuilder(block) })
+    contract(builder = { <!ERROR_IN_CONTRACT_DESCRIPTION!>callsInPlaceEffectBuilder(block)<!> })
     return block()
 }
 
@@ -41,6 +41,6 @@ inline fun case_2(block: () -> Unit) {
 
 // TESTCASE NUMBER: 3
 inline fun case_3(value_1: Int?, block: () -> Unit) {
-    contract({ returnsEffectBuilder(value_1); callsInPlaceEffectBuilder(block) })
+    contract({ <!ERROR_IN_CONTRACT_DESCRIPTION!>returnsEffectBuilder(value_1)<!>; <!ERROR_IN_CONTRACT_DESCRIPTION!>callsInPlaceEffectBuilder(block)<!> })
     return block()
 }

compiler/tests-spec/testData/diagnostics/notLinked/contracts/declarations/contractBuilder/common/neg/8.fir.kt

@@ -19,12 +19,12 @@ inline fun case_1(block: () -> Unit) {
 
 // TESTCASE NUMBER: 2
 inline fun case_2(block: () -> Unit) {
-    contract({ })
+    <!ERROR_IN_CONTRACT_DESCRIPTION!>contract({ })<!>
     return block()
 }
 
 // TESTCASE NUMBER: 3
 inline fun case_3(block: () -> Unit) {
-    contract(builder = { })
+    <!ERROR_IN_CONTRACT_DESCRIPTION!>contract(builder = { })<!>
     return block()
 }