### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When creating base-path-mappings on an API Gateway, there is a special `(none)` path when you don't specify a path during creation. Localstack stores this as `basePath: "(none)"` internally.
When you query to get the base paths, the URLs are escaped by the client (verified in both awscli and terraform) so the basePath is sent as `%28none%29` in the url.
Localstack doesn't appear to be decoding urls and when you attempt to get-base-path-mapping it fails in a string comparison of `(none)` to `%28none%29`.

```shell
> aws --endpoint-url=http://localhost:4566 apigateway get-base-path-mapping --domain-name example.com --base-path "(none)"

An error occurred (NotFoundException) when calling the GetBasePathMapping operation: Base path mapping not found: %28none%29
```

### Expected Behavior

When you attempt to get-base-path-mappings after creating one with the (none) path, it succeeds and returns the mapping.

```
> aws --endpoint-url=http://localhost:4566 apigateway get-base-path-mapping --domain-name example.com --base-path "(none)"

{
    "basePath": "(none)",
    "restApiId": "uyy4c3dsho",
    "stage": "dev"
}
```


### How are you starting LocalStack?

With the `localstack` script

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    make start

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

    awslocal apigateway create-rest-api --name "testgw"
    awslocal apigateway create-base-path-mapping --domain-name example.com --rest-api-id <from output above> --stage dev
    awslocal apigateway get-base-path-mapping --domain-name example.com --base-path "(none)"



### Environment

```markdown
- OS: fedora 34
- LocalStack: latest
```


### Anything else?

https://docs.aws.amazon.com/apigateway/api-reference/link-relation/basepathmapping-by-base-path/
resourceId=resource["id"],
            httpMethod="GET",
            pathWithQueryString="/foo",
            body='{"test": "val123"}',
            headers={"content-type": "application/json"},
        )
        self.assertEqual(200, response["ResponseMetadata"]["HTTPStatusCode"])
        self.assertEqual(200, response.get("status"))
        self.assertIn("response from", response.get("body"))
        self.assertIn("val123", response.get("body"))
        # Clean up
        lambda_client.delete_function(FunctionName=fn_name)
        client.delete_rest_api(restApiId=rest_api["id"])
    @staticmethod
    def start_http_backend(test_port):
        # test 
        class TestListener(ProxyListener):
            def forward_request(self, **kwargs):
                response = Response()
                response.status_code = 200
                result = {
                    "data": kwargs.get("data") or "{}",
                    "headers": dict(kwargs.get("headers")),
                }
                response._content = json.dumps(json_safe(result))
                return response
        proxy = start_proxy(test_port, update_listener=TestListener())
        return proxy
    @staticmethod
    def create_api_gateway_and_deploy(