Revamp the ktor-exposed portion and add new variant benchmarks with R2DBC

[ShreckYe]

Major changes:

• Bump all dependencies and toolchains to the latest.
• Migrate to Exposed v1 APIs.
• Add Exposed R2DBC benchmarks and restructure the code for better abstraction.
• Revert to use ParallelGC in all Ktor benchmarks. As run on my device, "Requests/sec" results of the db and json tests of the ktor portion are improved greatly.

Misc changes:

• Init the result mutable list and add elements with mapTo in the fortunes test instead to slightly improve some performance, as in the vertx-web-kotlinx portion.
• Split the code into multiple files and reorganize the code for better separation of concerns.
• Copy the optimized kotlinx-serialization Json configuration from the ktor portion.
• Fix inconsistent ports replacing all 8080s with 9090.