### 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/
)
        
        path = path.replace("{test_param1}", "foo1")
        url = gateway_request_url(api_id=result["id"], stage_name=self.TEST_STAGE_NAME, path=path)
        data = {}
        for method in ("GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"):
            body = json.dumps(data) if method in ("POST", "PUT", "PATCH") else None
            result = getattr(requests, method.lower())(url, data=body)
            if method != "DELETE":
                self.assertEqual(200, result.status_code)
                parsed_body = json.loads(to_str(result.content))
                self.assertEqual(method, parsed_body.get("httpMethod"))
            else:
                self.assertEqual(204, result.status_code)
    def test_apigateway_with_custom_authorization_method(self):
        apigw_client = aws_stack.connect_to_service("apigateway")
        # creat
        lambda_name = "apigw-lambda-%s" % short_uid()
        self.create_lambda_function(lambda_name)
        lambda_uri = aws_stack.lambda_function_arn(lambda_name)
        # creat
        api = apigw_client.create_rest_api(name="test-api", description="")
        api_id = api["id"]
        root_res_id = apigw_client.get_resources(restApiId=api_id)["items"][0]["id"]
        # creat
        authorizer = apigw_client.create_authorizer(
            restApiId=api_id,
            name="lambda_authorizer",
            type="TOKEN",
            authorizerUri="arn:aws:apigateway:us-east-1:lambda:path/ \