crdb-harness: Test Harness for CockroachDB

This crate provides a test harness for CockroachDB, as well as a build script which downloads a particular CockroachDB version into the OUT_DIR of a target directory.

Refer to ./tools/cockroachdb_version for the current version downloaded by this scripts (we may make this version configurable in the future).

lib.rs:

Facilities for managing a local database for development