### Is there an existing issue for this?

- [X] I have searched the existing issues

### Feature description

Currently, we always [calculate](https://github.com/localstack/localstack/blob/256b0de1f1a6085d3994e8d1322c763962ded2f0/localstack/services/kms/models.py#L229-L230) SHA256 digests for messages with `RAW` [MessageType](https://docs.aws.amazon.com/kms/latest/APIReference/API_Sign.html#API_Sign_RequestSyntax).

It is not clear if this is compatible with AWS. There are some reports like [this one](https://github.com/localstack/localstack/issues/6815#issuecomment-1309882776) about our implementation of Sign / Verify not working properly. Could be due to these digests.

What has to be done:
1. Should try to figure out how AWS calculates digests, whether the same algorithm is always used, or if digests are based on [SigningAlgorithm](https://docs.aws.amazon.com/kms/latest/APIReference/API_Sign.html#API_Sign_RequestSyntax). For this we can try importing the same key material into both AWS and LocalStack, use the resulting keys to sign the same message and then compare the signatures. If that works. If not - we can try just creating a key in AWS, sign a message with AWS, export the public key and then go through different digest algorithms in LocalStack, trying to verify the signed message with the obtained public key.
2. If the issue is really in our implementation of digests - should fix the digest logic.

### 🧑‍💻 Implementation

_No response_

### Anything else?

_No response_
import json
from datetime import datetime
from random import getrandbits
import pytest
from botocore.config import Config
from botocore.exceptions import ClientError
from cryptography.hazmat.primitives.asymmetric.padding import PKCS1v15
from cryptography.hazmat.primitives.serialization import load_der_public_key
from localstack.aws.accounts import get_aws_account_id
from localstack.testing.pytest.fixtures import _client
from localstack.utils.strings import short_uid
@pytest.fixture(scope="class")
def kms_client_for_region():
    def _kms_client(
        region_name: str = None,
    ):
        return _client("kms", region_name=region_name)
    return _kms_client
def _get_all_key_ids(kms_client):