[IR] CommonBackendContext and Symbols refactoring

* add [suspend]functionN factory factions
 * add `getContinuation` property
 * add `internalPackageName` property
 * fix lowerings

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmBackendContext.kt

@@ -45,6 +45,8 @@ class JvmBackendContext(
 
     override val configuration get() = state.configuration
 
+    override val internalPackageFqn = FqName("kotlin.jvm")
+
     internal fun getTopLevelClass(fqName: FqName): IrClassSymbol {
         val descriptor = state.module.getPackage(fqName.parent()).memberScope.getContributedClassifier(
             fqName.shortName(), NoLookupLocation.FROM_BACKEND

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmSymbols.kt

@@ -90,6 +90,9 @@ class JvmSymbols(
     override val coroutineSuspendedGetter: IrSimpleFunctionSymbol
         get() = TODO("not implemented")
 
+    override val getContinuation: IrSimpleFunctionSymbol
+        get() = TODO("not implemented")
+
     val javaLangClass: IrClassSymbol =
         context.getTopLevelClass(FqName("java.lang.Class"))