### 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/
self.assertEqual(200, resp.status_code)
        self.assertIn("executionArn", resp.content.decode())
        self.assertIn("startDate", resp.content.decode())
        # STEP 
        _prepare_method_integration(overwrite=True, action="StartSyncExecution")
        # invok
        test_data_1["name"] += "1"
        resp = requests.post(url, data=json.dumps(test_data_1))
        self.assertEqual(200, resp.status_code)
        content = json.loads(to_str(resp.content.decode()))
        self.assertEqual("SUCCEEDED", content.get("status"))
        self.assertEqual(test_data, json.loads(content.get("output")))
        # STEP 
        resp_templates = {APPLICATION_JSON: "$input.path('$.output')"}
        _prepare_method_integration(
            resp_templates=resp_templates, overwrite=True, action="StartSyncExecution"
        )
        # invok
        test_data_1["name"] += "2"
        resp = requests.post(url, data=json.dumps(test_data_1))
        self.assertEqual(200, resp.status_code)
        self.assertEqual(test_data, json.loads(to_str(resp.content.decode())))
        _prepare_method_integration(overwrite=True, action="DeleteStateMachine")
        # Remov
        resp = requests.post(url, data=json.dumps({"stateMachineArn": sm_arn}))
        self.assertEqual(200, resp.status_code)
        # Clean up
        lambda_client.delete_function(FunctionName=fn_name)
        client.delete_rest_api(restApiId=rest_api["id"])
    def test_api_gateway_http_integration_with_path_request_parameter(self):