[tx] Convert Clojure tests into Rust tests

[ncalexan]

The Clojure implementation has an extensive correctness test suite. Most of the tests look like:

1. install test schema;
2. transact a few assertions;
3. assert that datoms, transactions, or fulltext values table has following contents/new rows.
   Since our SQL schema is identical to the Clojure implementation, it should be easy to move the input and output data into .edn files and write a generic test harness to do those steps.

It might be finicky to get the transaction IDs, timestamps, and other ephemeral data correct. I wonder if we can rewrite :db/tx and :db/txInstant in controlled locations to get what we want? (This could require reader syntax like #value [:db/tx] or similar.)

[ncalexan]

I have a good start on the test framework locally, so please co-ordinate with me before doing anything in this area.