Move Kotlin test runner to partiql-lang-kotlin

[alancai98]

As part of #34, partiql-tests adds a validation check using a partiql-lang-kotlin test runner. This test runner was added to verify that the tests we're porting from partiql-lang-kotlin are ported correctly (e.g. have no typos, test environments are setup properly, etc) as part of Milestone 2.

After discussing with Josh, we think it would make the most sense to move the test runner outside of the partiql-tests repo and into partiql-lang-kotlin. The test repo should solely contain test data (other than some ISL validation) and not take any dependency on any implementation.

DoD

• Move Kotlin test runner gradle submodule to partiql-lang-kotlin