[2.x] Add HasApiTokens contract to complement trait

[wimski]

In a recent project using Sanctum I wanted to check if the User/Model/Authenticatable/whatever uses the HasApiTokens trait. Currently this can only be achieved by one of the following options:

// A. check trait usage
if (! in_array(HasApiTokens::class, class_uses($user)) {
    throw new Exception();
}

// B. check method existence
if (! method_exists($user, 'currentAccessToken')) {
    throw new Exception();
}

• Option A will work, but static analysis will not understand that $user has a specific set of methods.
• Option B does support static analysis, but is messy, because it doesn't really check for the trait (or specific contract).

Therefore I've added a contract to complement the trait.

use Laravel\Sanctum\Contracts\HasApiTokens as HasApiTokensContract;

if (! $user instanceof HasApiTokensContract::class) {
    throw new Exception();
}

This contract is not required for general use of Sanctum and is not a breaking change.

[wimski]

Thanks for merging!

When can I expect the next release containing this merge?