### 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/
from localstack.services.apigateway.helpers import (
    TAG_KEY_CUSTOM_ID,
    connect_api_gateway_to_sqs,
    gateway_request_url,
    get_resource_for_path,
    get_rest_api_paths,
)
from localstack.services.awslambda.lambda_api import add_event_source
from localstack.services.awslambda.lambda_utils import (
    LAMBDA_RUNTIME_NODEJS12X,
    LAMBDA_RUNTIME_PYTHON36,
)
from localstack.services.generic_proxy import ProxyListener
from localstack.services.infra import start_proxy
from localstack.utils import testutil
from localstack.utils.aws import aws_stack
from localstack.utils.common import clone, get_free_tcp_port, json_safe, load_file
from localstack.utils.common import safe_requests as requests
from localstack.utils.common import select_attributes, short_uid, to_str
from .test_lambda import TEST_LAMBDA_LIBS, TEST_LAMBDA_PYTHON
THIS_FOLDER = os.path.dirname(os.path.realpath(__file__))
TEST_SWAGGER_FILE = os.path.join(THIS_FOLDER, "files", "swagger.json")
TEST_IMPORT_REST_API_FILE = os.path.join(THIS_FOLDER, "files", "pets.json")
TEST_LAMBDA_ECHO_FILE = os.path.join(THIS_FOLDER, "lambdas", "lambda_echo.py")
TEST_LAMBDA_HANDLER_JS = os.path.join(THIS_FOLDER, "lambdas", "lambda_handler.js")
ApiGatewayLambdaProxyIntegrationTestResult = namedtuple(
    "ApiGatewayLambdaProxyIntegrationTestResult",
    [
        "data",
        "resource",