### 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/
client = aws_stack.connect_to_service("apigateway")
        response = client.create_rest_api(name="my_api", description="this is my api")
        rest_api_id = response["id"]
        _name = "testModel"
        description = "test "
        content_type = "application/json"
        # when 
        result = client.get_s(restApiId=rest_api_id)
        self.assertEqual([], result["items"])
        # add a 
        client.create_(
            restApiId=rest_api_id,
            name=_name,
            description=description,
            contentType=content_type,
        )
        # get m
        result = client.get_s(restApiId=rest_api_id)
        self.assertEqual(_name, result["items"][0]["name"])
        self.assertEqual(description, result["items"][0]["description"])
        
        client.delete_rest_api(restApiId=rest_api_id)
    def test_request_validator(self):
        client = aws_stack.connect_to_service("apigateway")
        response = client.create_rest_api(name="my_api", description="this is my api")
        rest_api_id = response["id"]
        # CREATE