LP:459714 - Proper test suite for OQGRAPH

Given that OQGRAPH is not a 'normal' general purpose storage engine, we can't simply derive a test suite from existing ones.
However, we would like to test all aspects of the engine, including interaction in complex join constructs and replication.

Perhaps some basics can be adapted from existing tests, the rest will have to be new.
This will probably be a step-wise and ongoing thing. If you can help, please do!

What we need: (based on feedback from Philip Stoev)

• a complete MTR test suite that covers at least the following:

• INSERTS, especially with weight and those that will be rejected by the engine;
• the SELECT statements that are accepted by the engine, as described in the manual, including those with latch=0 or latch = NULL;
• the DML/DDL/ALTER statements that are and are not accepted by the engine, so that all the engine capabilities the handler advertises and all the API calls are exercised;
• a dataset that is sized appropriately for MTR execution (10K nodes?). Either in the form of INSERT statements or a stored procedure, plus some SELECT queries on top of that dataset;