### 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/
integrationHttpMethod="GET",
            type="HTTP",
            uri=backend_url,
            timeoutInMillis=3000,
            contentHandling="CONVERT_TO_BINARY",
            requestParameters={"integration.request.path.id": "method.request.path.id"},
        )
        client.create_deployment(restApiId=api_id, stageName="test")
        def _test_invoke(url):
            result = requests.get(url)
            content = json.loads(to_str(result.content))
            self.assertEqual(200, result.status_code)
            self.assertRegex(
                content["headers"].get(HEADER_LOCALSTACK_REQUEST_URL),
                "http://.*localhost.*/person/123",
            )
        for use_hostname in [True, False]:
            for use_ssl in [True, False] if use_hostname else [False]:
                url = self._get_invoke_endpoint(
                    api_id,
                    stage="test",
                    path="/person/123",
                    use_hostname=use_hostname,
                    use_ssl=use_ssl,
                )
                _test_invoke(url)
        
        client.delete_rest_api(restApiId=api_id)
        proxy.stop()
    def _get_invoke_endpoint(