### 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/
region_details = APIGatewayRegion.get()
    vpc_link_id = get_vpc_link_id_from_path(path)
    if vpc_link_id:
        vpc_link = region_details.vpc_links.get(vpc_link_id)
        if vpc_link is None:
            return make_error_response('VPC link ID "%s" not found' % vpc_link_id, code=404)
        return make_json_response(to_vpc_link_response_json(vpc_link))
    result = region_details.vpc_links.values()
    result = [to_vpc_link_response_json(r) for r in result]
    result = {"items": result}
    return result
def add_vpc_link(path, data):
    region_details = APIGatewayRegion.get()
    result = common.clone(data)
    result["id"] = common.short_uid()
    result["status"] = "AVAILABLE"
    region_details.vpc_links[result["id"]] = result
    return make_json_response(to_vpc_link_response_json(result))
def update_vpc_link(path, data):
    region_details = APIGatewayRegion.get()
    vpc_link_id = get_vpc_link_id_from_path(path)
    vpc_link = region_details.vpc_links.get(vpc_link_id)
    if vpc_link is None:
        return make_error_response('VPC link ID "%s" not found' % vpc_link_id, code=404)
    result = apply_json_patch_safe(vpc_link, data["patchOperations"])
    return make_json_response(to_vpc_link_response_json(result))
def delete_vpc_link(path):