Support POST Object requests

[afranken]

Description

Not all parameters are supported right now.

Also adds tests for large uploads through presigned URLs.

Related Issue

Fixes #2200

Tasks

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

[Copilot]

Pull Request Overview

This PR adds support for POST object requests and enhances test coverage for large uploads via presigned URLs.

• Consolidates HTTP parameter constants for DELETE operations.
• Adds an overloaded toTempFile method in ServiceBase for processing POST object uploads.
• Implements the new postObject endpoint in ObjectController along with updated integration tests for both POST and PUT presigned URL workflows.

Reviewed Changes

Copilot reviewed 8 out of 20 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
server/src/main/java/com/adobe/testing/s3mock/util/AwsHttpParameters.java	Reorders and groups DELETE-related constants to support POST requests.
server/src/main/java/com/adobe/testing/s3mock/service/ServiceBase.java	Introduces a new toTempFile(InputStream) method for POST object handling.
server/src/main/java/com/adobe/testing/s3mock/ObjectController.java	Implements a new postObject endpoint for POST object requests.
server/src/main/java/com/adobe/testing/s3mock/BucketController.java	Cleans up unused import declarations.
integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/S3TestBase.kt	Adjusts test utilities and adds S3PostObjectPresigner support.
integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/PresignedUrlIT.kt	Adds integration tests for both POST and PUT presigned URL operations.
README.md	Updates documentation to reflect support for PostObject.
CHANGELOG.md	Updates changelog for the 4.1.0 release.

Files not reviewed (12)

• build-config/pom.xml: Language not supported
• docker/pom.xml: Language not supported
• integration-tests/pom.xml: Language not supported
• pom.xml: Language not supported
• server/pom.xml: Language not supported
• server/src/main/resources/application.properties: Language not supported
• testsupport/common/pom.xml: Language not supported
• testsupport/junit4/pom.xml: Language not supported
• testsupport/junit5/pom.xml: Language not supported
• testsupport/pom.xml: Language not supported
• testsupport/testcontainers/pom.xml: Language not supported
• testsupport/testng/pom.xml: Language not supported

Comments suppressed due to low confidence (2)

server/src/main/java/com/adobe/testing/s3mock/util/AwsHttpParameters.java:37

• [nitpick] Consider grouping the DELETE constant declaration together with its corresponding NOT_DELETE constant to improve code clarity and maintainability.

public static final String DELETE = "delete";

integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/PresignedUrlIT.kt:86

• [nitpick] Using randomMBytes.inputStream() multiple times to compute the digest may introduce issues if the underlying source is not repeatable. Consider computing and caching the digest once for use in subsequent comparisons to improve test stability.

val expectedEtag = "\"${DigestUtil.hexDigest(randomMBytes.inputStream())}\""