add tpc-ds tests and property-based testing utilities

This change introduces a new `property_based.rs` test utility which lets us evaluate
correctness using properties. These are useful for evaluating correctness when
we do not know the expected output of a test (ex. if we were to fuzz the database
with randomized data or randomzed queries, then we can only verify the output using
properties). The two oracles are
- ResultSetOracle: Compares the result set between single node and distributed datafusion
- OrderingOracle: Uses plan properties to figure out the expected ordering and asserts it

This change does not introduce a fuzz test, but it introduces a TPC-DS test. This test
randomly generates data using the duckdb CLI and runs 99 queries on a distributed cluster.
The query outputs are validated against single-node datafusion using test utils in
`metamorphic.rs`. This test also randomizes the test cluster parameters - there's no harm
in doing so.

Next steps:
- Add fuzzing
  - Now that we have property-based testing utils, we can properly fuzz the project
    using SQLancer
  - SQLancer produces INSERT and SELECT statements which we could point at a datafusion
    distributed cluster and verify against single node datafusion
  - Although it doesn't support nested select statements, 70% of the queries were valid
    datafusion queries, meaning these are good test cases for us
- Add metrics oracle to validate output_rows metric / metrics propagation

Author: jayshrivastava

.gitignore

@@ -1,4 +1,5 @@
 /.idea
 /target
 /benchmarks/data/
-testdata/tpch/data/
+testdata/tpch/data/
+testdata/tpcds/data/