### 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/
restApiId=api_id,
            resourceId=api_resource["id"],
            httpMethod="GET",
            integrationHttpMethod="POST",
            type="AWS",
            uri=target_uri,
            timeoutInMillis=3000,
            contentHandling="CONVERT_TO_BINARY",
            requestTemplates={"application/json": '{"param1": "$input.params(\'param1\')"}'},
        )
        integration_keys = [
            "httpMethod",
            "type",
            "passthroughBehavior",
            "cacheKeyParameters",
            "uri",
            "cacheNamespace",
            "timeoutInMillis",
            "contentHandling",
            "requestParameters",
        ]
        self.assertEqual(200, rs["ResponseMetadata"]["HTTPStatusCode"])
        for key in integration_keys:
            self.assertIn(key, rs)
        self.assertNotIn("responseTemplates", rs)
        apigw_client.create_deployment(restApiId=api_id, stageName=self.TEST_STAGE_NAME)
        rs = apigw_client.get_integration(
            restApiId=api_id, resourceId=api_resource["id"], httpMethod="GET"
        )
        self.assertEqual(200, rs["ResponseMetadata"]["HTTPStatusCode"])