Create cypher_raw parser function

[JeroenDeDauw]

For demo purposes. This will not be turned into a more capable function. We might instead add #cypher or similar later in the project.

AC:

• parser function exists {{#cypher_raw: cypher query be here}}
• cypher query is executed
• Write queries are rejected by using CypherQueryFilter
• raw query response is output. Output can be JSON encoded in a codeblock or similar

Backend services for executing Cypher already exist.