Add Kotlin SDK ITs, simplifications

[afranken]

Description

Use new Kotlin SDK for ITs
Use simplified Kotlin builder syntax in tests

Related Issue

N/A

Tasks

• I have signed the CLA.
• I have written tests and verified that they fail without my change.

[Copilot]

Pull Request Overview

This PR updates the integration tests to use the new Kotlin SDK and simplified Kotlin builder syntax for S3 operations. Key changes include:

• Updating all S3 client and request builder invocations to use Kotlin DSL lambda style.
• Renaming credential variables consistently to s3AccessKeyId and s3SecretAccessKey.
• Introducing a new createS3ClientKotlin function for the Kotlin SDK and adding a new IT file.

Reviewed Changes

Copilot reviewed 3 out of 5 changed files in this pull request and generated no comments.

File	Description
integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/S3TestBase.kt	Refactor of S3 client creation and request builders using Kotlin DSL, plus variable renaming.
integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/KotlinSDKIT.kt	New integration test using the new Kotlin SDK.
integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/AclITV2.kt	Updated bucket and ACL operations to leverage Kotlin DSL.

Files not reviewed (2)

• integration-tests/pom.xml: Language not supported
• pom.xml: Language not supported

Comments suppressed due to low confidence (1)

integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/S3TestBase.kt:288

• [nitpick] The nested let chain used for constructing 'normalizedName' may reduce readability. Consider refactoring this block by introducing intermediary variables to improve clarity.

val normalizedName = testInfo.testMethod.get().name.let {