Add tests for Ktor using an async database layer

[Whoops]

This adds a couple additional tests with Ktor, but using non-blocking database clients. In theory this should reduce the overhead of using blocking JDBC calls with a work pool.

I actually went ahead and implemented two different clients since I'm curious how they perform. Jasync-sql is interesting in that it has Kotlin coroutines integration, which makes the code actually more natural than the JDBC based tests. Reactive-PG-Client seems more feature full, and is the same client used in the Vert.x tests.

[NateBrady23]

Since this is a permutation for ktor, we'd prefer this to be in the Kotlin/ktor directory. You can add these tests to that benchmark_config.json

[Whoops]

Done, I've moved it and the existing tests into subdirectories under the existing ktor directory. I'm hoping that approach is acceptable, and I'm not sure how I'd integrate them into a single build.

[NateBrady23]

Yeah, that approach is great. No need to make them a single build.