Fixes preparation of filters and revert breaking changes

[michgeek]

Change Summary

• Simplify the syntax of the filters preparation for a more readable one and also prevent the case when $whereFilter is empty but $whereInFilter is filled. This is issue is related to https://github.com/typesense/laravel-scout-typesense-driver/issues/43
• Revert changes that is causing document update breakage. Reported in https://github.com/typesense/laravel-scout-typesense-driver/issues/45. Same PR as https://github.com/typesense/laravel-scout-typesense-driver/pull/47

Concerning issue #43

It takes care of the following cases :

$whereFilter = 'a';
$whereInFilter = 'b';
// Expected 'a && b'

$whereFilter = 'a';
$whereInFilter = '';
// Expected 'a'

$whereFilter = '';
$whereInFilter = 'b';
// Expected 'b'

$whereFilter = '';
$whereInFilter = '';
// Expected ''

PR Checklist

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[karakhanyans]

Hi @michgeek #47 was merged. I will close this PR for now and we can add filters back later. Thank you.