Parse model hooks for refs

Add a parse pass for model hooks, parse them like models
Attach the hook refs as if they were on the model
Add a test exercising refs


automatic commit by git-black, original commits:
  22db36c

core/dbt/parser/base.py

@@ -223,7 +223,7 @@ def _create_parsetime_node(
             )
             raise ParsingException(msg, node=node)
 
-    def _context_for(
+    def _context_for(self, parsed_node: IntermediateNode, config: ContextConfig) -> Dict[str, Any]:
         self, parsed_node: IntermediateNode, config: ContextConfig
     ) -> Dict[str, Any]:
         return generate_parser_model_context(
@@ -312,8 +312,7 @@ def update_parsed_node_config(
 
         # at this point, we've collected our hooks. Use the node context to
         # render each hook and collect refs/sources
-        hooks = list(itertools.chain(parsed_node.config.pre_hook,
-                                     parsed_node.config.post_hook))
+        hooks = list(itertools.chain(parsed_node.config.pre_hook, parsed_node.config.post_hook))
         # skip context rebuilding if there aren't any hooks
         if not hooks:
             return