[FIR] Rename FirDeclaration.session to declarationSiteSession

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt

@@ -200,7 +200,7 @@ class FirElementSerializer private constructor(
     @OptIn(ExperimentalStdlibApi::class)
     private fun FirClass<*>.declarations(): List<FirCallableMemberDeclaration<*>> = buildList {
         val memberScope =
-            defaultType().scope(session, scopeSession, FakeOverrideTypeCalculator.DoNothing)
+            defaultType().scope(declarationSiteSession, scopeSession, FakeOverrideTypeCalculator.DoNothing)
                 ?: error("Null scope for $this")
 
         fun addDeclarationIfNeeded(symbol: FirCallableSymbol<*>) {
@@ -946,17 +946,17 @@ class FirElementSerializer private constructor(
         ): FirElementSerializer {
             val parentClassId = klass.symbol.classId.outerClassId
             val parent = if (parentClassId != null && !parentClassId.isLocal) {
-                val parentClass = klass.session.symbolProvider.getClassLikeSymbolByFqName(parentClassId)!!.fir as FirRegularClass
+                val parentClass = klass.declarationSiteSession.symbolProvider.getClassLikeSymbolByFqName(parentClassId)!!.fir as FirRegularClass
                 parentSerializer ?: create(scopeSession, parentClass, extension, null, typeApproximator)
             } else {
-                createTopLevel(klass.session, scopeSession, extension, typeApproximator)
+                createTopLevel(klass.declarationSiteSession, scopeSession, extension, typeApproximator)
             }
 
             // Calculate type parameter ids for the outer class beforehand, as it would've had happened if we were always
             // serializing outer classes before nested classes.
             // Otherwise our interner can get wrong ids because we may serialize classes in any order.
             val serializer = FirElementSerializer(
-                klass.session,
+                klass.declarationSiteSession,
                 scopeSession,
                 klass,
                 Interner(parent.typeParameters),