Add an easy way to see all queries that metabase sends (log all queries)

@paoliniluis often wants to see the actual queries that metabase issues. He had learned which logging level in the qp would allow this. This has recently changed. He now has to have a quite chatty low level enabled in order to see queries. This leaves him flying blind.

The feature:
we want to be able to easily see all queries that metabase sends over (question: what about sync? this can be quite a lot). For the time being lets go with user queries.

No files, tests, or entry points are named. Start by locating the query-dispatch and logging code in the Clojure project, then determine how user queries can be logged without requiring a broadly chatty logging level. Done means there is an easy way to see all user queries Metabase sends, while sync queries remain out of scope for now.

Written by the indexing model from the issue text.