Allow deepMerge on custom properties

[mpociot]

This PR is the JS counterpart of inertiajs/inertia-laravel#732

For whatever reason, the tests did time out when I tried to run them via npx for my newly created API route. I did test it manually by running the server though.
Not really sure what I did wrong.

[HichemTab-tech]

For whatever reason, the tests did time out when I tried to run them via npx for my newly created API route. I did test it manually by running the server though.
Not really sure what I did wrong.

Happened to me too in a previous PR, i just kept running the tests until it worked, i think we should increase the timeout a bit.

[pascalbaljet]

Thanks @mpociot, this looks great! I'll add another test for props with multiple strategies. I expect you added support for this if you have resources like this:

$data = [
    'users' => [
        ['id' => 1, 'name' => '...'],
        ['id' => 2, 'name' => '...'],
    ],
    'companies' => [
        ['id' => 1, 'name' => '...'],
        ['id' => 2, 'name' => '...'],
    ],
];

Inertia::render('Dashboard', [
    'results' => Inertia::deepMerge($data, ['users.id', 'companies.id']),
]);

[pascalbaljet]

Updated the test in bdc5ef6 to test multiple arrays with different keys and unique keys. Thanks again!