[9.x] Passthru implode from query builder

[axlon]

This PR fixes the usage of the implode() method on a eloquent builder.

Before:

>>> App\Models\User::query()->take(3)->implode('id', ',')
=> Illuminate\Database\Eloquent\Builder {#5256}

>>> App\Models\User::query()->take(3)->toBase()->implode('id', ',')
=> "1,2,3"

After:

>>> App\Models\User::query()->take(3)->implode('id', ',')
=> "1,2,3"

>>> App\Models\User::query()->take(3)->toBase()->implode('id', ',')
=> "1,2,3"

An argument could be made that this is a breaking change, but the way this method works currently makes it unusable so its unlikely to break anyone's project. Right now developers are probably using ->toBase()->implode(...) which will still work the same way.