[LL API] Support nested type aliases in file-based declaration provider

analysis/low-level-api-fir/testdata/fileBasedDeclarationProvider/nestedTypeAlias.kt

@@ -0,0 +1,7 @@
+// TYPE_ALIAS: test/Foo.Bar
+
+package test
+
+class Foo {
+    typealias Bar = Foo
+}