### 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/
"usagePlanId": usage_plan_id,
                    "keyId": api_key["id"],
                    "keyType": key_type,
                }
                client.create_usage_plan_key(**payload)
                api_keys.append(api_key["value"])
        response = requests.put(
            url,
            json.dumps({"id": "id1", "data": "foobar123"}),
        )
        # when 
        self.assertEqual(403, response.status_code)
        # check 
        for key in api_keys:
            response = requests.put(
                url,
                json.dumps({"id": "id1", "data": "foobar123"}),
                headers={"X-API-Key": key},
            )
            # when 
            self.assertEqual(200, response.status_code)
    def test_import_rest_api(self):
        rest_api_name = "restapi-%s" % short_uid()
        client = aws_stack.connect_to_service("apigateway")
        rest_api_id = client.create_rest_api(name=rest_api_name)["id"]
        spec_file = load_file(TEST_SWAGGER_FILE)
        rs = client.put_rest_api(restApiId=rest_api_id, body=spec_file, mode="overwrite")
        self.assertEqual(200, rs["ResponseMetadata"]["HTTPStatusCode"])
        rs = client.get_resources(restApiId=rest_api_id)
        self.assertEqual(