CustomLocator plugin takes all selector as key

#### What are you trying to achieve?
I'd like to use a custom locator and a suffix css selector

#### What do you get instead?
Instead of concatening the custom locator and the end of the css selector, I've got a full length of customLocator

> Provide test source code if related

```js
// What I want to achieve:
I.click('[data-testid=register_button] option:first-child()');
// ==> gives OK

// When using the custom locator:
I.click('$register_button option:first-child()');
// ==> gives [1] Error | Error: Clickable element ".//*[@data-testid='register_button option:first-child()']" was not found by text|CSS|XPath
```

### Details

* CodeceptJS version: 3.0.5
* NodeJS Version: 14.16
* Operating System: Linux
* Configuration file:

```js
plugins: {
allure: {},
pauseOnFail: {},
customLocator: {
enabled: true,
attribute: 'data-testid',
showActual: true,
},
},
```

Would it be possible to add a new option like 'final delimiter'? (space by default) It would truncate the locator to be used?