Fix s3 crt checksum calc

[sbiscigl]

Description of changes:

right now we don't propagate flexsum configuration to S3Crt, this changes to propagate the configuraiton. Previously the following request would fail.

#include <aws/core/Aws.h>
#include <aws/core/utils/HashingUtils.h>
#include <aws/s3-crt/S3CrtClient.h>
#include <aws/s3-crt/model/PutObjectRequest.h>

using namespace Aws;
using namespace Aws::Client;
using namespace Aws::S3Crt;
using namespace Aws::S3Crt::Model;

static auto ALLOC_TAG = "sdk-example";
static auto BUCKET_NAME = "bucket-name";
static auto KEY_NAME = "test-key";

auto main() -> int
{
    SDKOptions options;
    options.loggingOptions.logLevel = Utils::Logging::LogLevel::Debug;
    InitAPI(options);
    {
        S3CrtClient client;
        auto putObjectRequest = PutObjectRequest().WithBucket(BUCKET_NAME)
                                                  .WithKey(KEY_NAME);

        std::shared_ptr<IOStream> data = Aws::MakeShared<StringStream>(ALLOC_TAG,
            "test string",
            std::ios_base::in | std::ios_base::binary);

        putObjectRequest.SetBody(data);
        putObjectRequest.SetChecksumAlgorithm(ChecksumAlgorithm::CRC32);
        const auto putObjectResult = client.PutObject(putObjectRequest);
        assert(putObjectResult.IsSuccess());
    }
    ShutdownAPI(options);
    return 0;
}

Additionally this fixes memory leaks that existed in the CRT client that were not being tested before that now exist. This PR additionally re-enables the CRT integration tests so that we don't accidentally miss these issues anymore either.

Check all that applies:

• Did a review by yourself.
• Added proper tests to cover this PR. (If tests are not applicable, explain.)
• Checked if this PR is a breaking (APIs have been changed) change.
• Checked if this PR will not introduce cross-platform inconsistent behavior.
• Checked if this PR would require a ReadMe/Wiki update.

Check which platforms you have built SDK on to verify the correctness of this PR.

• Linux
• Windows
• Android
• MacOS
• IOS
• Other Platforms

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[SergeyRyabinin]

I think Begin() goes here and End() right after "ShutdownAPI"

[sbiscigl]

this is copy and pasted more or less from what we already do and how we use it in the crt test already