…nd benchmark code into the module "integrated"

IntelliJ IDEA Code Analysis shows there are 5 errors.

…tgresql.api" file

…ode to resolve

…gConnection` for different DBs, replacing them with `Pool` and `Connection`

A new `withTypedTransaction` function is added and `withPgTransaction` is moved into the `postgresql` package.

Major changes:

1. move some code to finer-grained subpackages
1. initially overhaul the APIs related to the creation of Vert.x SQL clients and `DatabaseClient`s

   The `create...andSetRole` functions are removed, and their functionalities are merged into the `create...` functions.

1. add TODOs as guidance for the remaining work

1. move code related to `PostgreSQL` into the `postgreql` package
1. refactor the Vert.x `SqlClient` and Exposed `Database` creation APIs to be more configurable and straightforward
1. extract some common functions for JDBC, Exposed, and Vert.x
1. move the example code into the `main` source set
1. remove the extra `DatabaseClient` creation APIs `create*DatabaseClient`
1. adopt `EvscConfig` as the single-source-of-truth client config
1. add some more TODOs
1. update the example code README.md correspondingly

…current API design

…users usually don't call them directly and by doing this we don't forget to pass arguments in a caller

The corresponding commit: huanshankeji/kotlin-common@1b93c18

…ed" module

```text
Execution failed for task ':exposed-vertx-sql-client-integrated:compileBenchmarksKotlin'.
> Could not resolve all files for configuration ':exposed-vertx-sql-client-integrated:benchmarksCompileClasspath'.
   > Could not resolve all dependencies for configuration ':exposed-vertx-sql-client-integrated:benchmarksCompileClasspath'.
      > Could not find io.vertx:vertx-sql-client:.
        Required by:
            project :exposed-vertx-sql-client-integrated > project :exposed-vertx-sql-client-core
```

…odule

…-mapper" into these modules

Miscellaneous changes:
1. remove the PostgreSQL dependencies in the "core" module
1. add and use the `@InternalApi` opt-in annotation
1. update `executeExpression` to throw since the core module doesn't depend on the "sql-dsl" module anymore
1. add an example of `DatabaseClient.selectExpression` with `exists` in the example code

…ConnectionEach10KLocalTransactions`

…d `multiThreadConcurrent10KTransactionsWithImplicitThreadLocalDatabases` into the benchmark code, fix `singleThreadConcurrent10KTransactions` which actually runs on multiple threads instead of one BTW, and improve `multiThreadConcurrent10KTransactionsWithSharedDatabase` BTW

… extract `awaitAsync10K`