update postgres test container

- update README.md
- update PostgresContainer
  - add TestExecutionListeners
  - remove ExtendWith
- update PostgresInitializer
  - cleanup
  - use properties for script and container
  - add afterTestClass
  - add beforeTestClass
  - extend TestExecutionListener
- remove PostgresExtension
- add debug logging to PostgresExecutor
- add ContainerUtils
- add dependencies
- extract function from PostgresExtension to PostgresExecutor

src/main/kotlin/ltd/hlaeja/test/container/PostgresContainer.kt

@@ -1,11 +1,12 @@
 package ltd.hlaeja.test.container
 
-import org.junit.jupiter.api.extension.ExtendWith
 import org.springframework.test.context.ContextConfiguration
+import org.springframework.test.context.TestExecutionListeners
+import org.springframework.test.context.TestExecutionListeners.MergeMode.MERGE_WITH_DEFAULTS
 
 @Suppress("unused")
 @Retention(AnnotationRetention.RUNTIME)
 @Target(AnnotationTarget.CLASS)
-@ExtendWith(PostgresExtension::class)
 @ContextConfiguration(initializers = [PostgresInitializer::class])
+@TestExecutionListeners(listeners = [PostgresInitializer::class], mergeMode = MERGE_WITH_DEFAULTS)
 annotation class PostgresContainer