Add a `headers_jsons` grep argument

[abompard]

Now that there is a JSONB index on the headers column, we could add a grep argument that would make use of it. It could look something like:

--- a/datanommer.models/datanommer/models/__init__.py
+++ b/datanommer.models/datanommer/models/__init__.py
@@ -395,6 +395,8 @@ class Message(DeclarativeBase):
         not_topics=None,
         agents=None,
         not_agents=None,
+        headers_jsons=None,
+        headers_jsons_and=None,
         contains=None,
     ):
         """Flexible query interface for messages.
@@ -436,6 +438,8 @@ class Message(DeclarativeBase):
         not_topics = not_topics or []
         agents = agents or []
         not_agents = not_agents or []
+        headers_jsons = headers_jsons or []
+        headers_jsons_and = headers_jsons_and or []
         contains = contains or []
 
         Message = cls
@@ -470,6 +474,11 @@ class Message(DeclarativeBase):
         if agents:
             query = query.where(or_(*(Message.agent_name == agent for agent in agents)))
 
+        if headers_jsons:
+            query = query.where(or_(*(Message.headers.path_match(path) for path in headers_jsons)))
+        if headers_jsons_and:
+            query = query.where(and_(*(Message.headers.path_match(path) for path in headers_jsons_and)))
+
         if contains:
             query = query.where(or_(*(Message.msg.like(f"%{contain}%") for contain in contains)))