FIR: Support context receivers in Fir2Ir

compiler/fir/semantics/src/org/jetbrains/kotlin/fir/declarations/ImplicitReceiverUtils.kt

@@ -90,9 +90,10 @@ fun SessionHolder.collectTowerDataElementsForClass(owner: FirClass, defaultType:
     }
 
     val thisReceiver = ImplicitDispatchReceiverValue(owner.symbol, defaultType, session, scopeSession)
-    val contextReceivers = (owner as? FirRegularClass)?.contextReceivers?.map {
+    val contextReceivers = (owner as? FirRegularClass)?.contextReceivers?.mapIndexed { index, receiver ->
         ContextReceiverValueForClass(
-            owner.symbol, it.typeRef.coneType, it.labelName, session, scopeSession,
+            owner.symbol, receiver.typeRef.coneType, receiver.labelName, session, scopeSession,
+            contextReceiverNumber = index,
         )
     }.orEmpty()
 
@@ -248,6 +249,9 @@ typealias FirLocalScopes = PersistentList<FirLocalScope>
 fun FirCallableDeclaration.createContextReceiverValues(
     sessionHolder: SessionHolder,
 ): List<ContextReceiverValueForCallable> =
-    contextReceivers.map {
-        ContextReceiverValueForCallable(symbol, it.typeRef.coneType, it.labelName, sessionHolder.session, sessionHolder.scopeSession)
+    contextReceivers.mapIndexed { index, receiver ->
+        ContextReceiverValueForCallable(
+            symbol, receiver.typeRef.coneType, receiver.labelName, sessionHolder.session, sessionHolder.scopeSession,
+            contextReceiverNumber = index,
+        )
     }