Allow annotating models and routes using sorbet's static checks

[wteuber]

This PR allows Annotate to recognize and keep Sorbet's static checks sigils.

Diff after running annotate for models and routes with Sorbet static check sigils:

Before

-# typed: true
 # frozen_string_literal: true
 
+# == Schema Information
+#
+# Table name: …
+#
+#  …
+#
+# typed: true
+

After

 # typed: true
 # frozen_string_literal: true
 
+# == Schema Information
+#
+# Table name: …
+#
+#  …
+#