#291 implement sortByMany

[shafi-]

This PR aims to add support for sortByMany method asked in the issue #291
Corresponding Laravel implementation https://github.com/laravel/framework/blob/8.x/src/Illuminate/Collections/Collection.php#L1325

[ecrmnn]

Thanks for the PR, @shafi- 🙏

I see I've made the mistake of thinking this was a public method that should be exposed to the user.

On a closer look, I see that sortByMany is called from the sortBy method, when the user passes an array or closure.
https://github.com/laravel/framework/blob/8.x/src/Illuminate/Collections/Collection.php#L1289

Could you please update you PR to reflect this?

[shafi-]

@ecrmnn, Thanks for your response.

Updated it. Let me know if it is fine or not.