Fix bug in parsing of super expression (#1364)

pkl-core/src/test/files/LanguageSnippetTests/input/parser/spread.pkl

@@ -0,0 +1,15 @@
+
+local baz = new Dynamic {}
+
+local foo = new Dynamic {
+  bar = 1
+}
+
+qux {
+  (foo) {
+    ...super.bar
+    (baz) {
+      qux = 1
+    }
+  }
+}

pkl-core/src/test/files/LanguageSnippetTests/output/parser/spread.pcf

@@ -0,0 +1,8 @@
+qux {
+  new {
+    bar = 1
+    new {
+      qux = 1
+    }
+  }
+}