### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When attempting to sign some document using Localstack KMS inside a lambda container (also running on localstack), the localstack KMS listener returns some unknown error.

The KMS key and lambda containers have been created from the same CDK app deploy, and I can see all the resources in the localstack web console.

The test application I'm using to prove this behaviour is available here:
https://github.com/LukaHedt/localstack_kms_test

Instructions to run are in the main Readme, and the `/localstack/Readme.md` file.

`aws-sdk` returns an unknown error, and the localstack docker logs that I receive are available here:
https://pastebin.com/58Z3fXi3

Have done an amount of testing and can confidently claim the following:
- Have tested on multiple machines with the same outcome
- Doesn’t make a difference if I specify an ARN or a KeyID in the signing request
- Downgrading localstack versions either didn’t make a difference, or I couldn’t actually deploy a localstack container with version 0.12.20 or lower.

### Expected Behavior

KMS Sign should return a signature for the given payload.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

Test application demonstrating the current behaviour is available here:

https://github.com/LukaHedt/localstack_kms_test

Full instructions to run are in the `/localstack/Readme.md` file.


### Environment

```markdown
- OS: MacOS Monteray 12.3
- LocalStack: 0.14.0
```


### Anything else?

_No response_
"""
    Unfortunately, SQS uses a rare interpretation of the XML protocol: It uses HTML entities within XML tag text nodes.
    For example:
    - Normal XML serializers: <Message>No need to escape quotes (like this: ") with HTML entities in XML.</Message>
    - SQS XML serializer: <Message>No need to escape quotes (like this: &quot;) with HTML entities in XML.</Message>
    None of the prominent XML frameworks for python allow HTML entity escapes when serializing XML.
    This serializer implements the following workaround:
    - Escape quotes and \r with their HTML entities (&quot; and &#xD;).
    - Since & is (correctly) escaped in XML, the serialized string contains &amp;quot; and &amp;#xD;
    - These double-escapes are corrected by replacing such strings with their original.
    """
    def _default_serialize(self, xmlnode: ETree.Element, params: str, _, name: str) -> None: