### 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/
test_port = get_free_tcp_port()
        backend_url = "http://localhost:%s%s" % (test_port, self.API_PATH_HTTP_BACKEND)
        old_config = config.DISABLE_CUSTOM_CORS_APIGATEWAY
        config.DISABLE_CUSTOM_CORS_APIGATEWAY = False
        
        proxy = self.start_http_backend(test_port)
        
        result = self.connect_api_gateway_to_http(
            int_type, "test_gateway2", backend_url, path=self.API_PATH_HTTP_BACKEND
        )
        url = gateway_request_url(
            api_id=result["id"],
            stage_name=self.TEST_STAGE_NAME,
            path=self.API_PATH_HTTP_BACKEND,
        )
        
        origin = "localhost"
        result = requests.options(url, headers={"origin": origin})
        self.assertEqual(result.status_code, 200)
        self.assertTrue(
            re.match(result.headers["Access-Control-Allow-Origin"].replace("*", ".*"), origin)
        )
        self.assertIn("POST", result.headers["Access-Control-Allow-Methods"])
        self.assertIn("PATCH", result.headers["Access-Control-Allow-Methods"])
        custom_result = json.dumps({"foo": "bar"})
        
        result = requests.get(url)
        self.assertEqual(200, result.status_code)