Support indexing with any type which implmented __index__

[aisk]

Proposed changes

Any type which implemented __index__ can be used to indexing mlx array, so we can use numpy scalar to indexing array.

bool is not supported also it implemented __index__ (actually, bool is a subclass of int) because it's to quirky.

Close: #2710

Checklist

Put an x in the boxes that apply.

• I have read the CONTRIBUTING document
• I have run pre-commit run --all-files to format my code / installed pre-commit prior to committing changes
• I have added tests that prove my fix is effective or that my feature works
• I have updated the necessary documentation (if needed)

[zcbenz]

Can you fix the linting error? The code looks good to me.

[angeloskath]

Numpy arrays and mlx arrays do not implement __index__ so no need for the extra checks.

[angeloskath]

I think this should simply be return PyIndex_Check(obj.ptr()) && !nb::isinstance<nb::bool_>(obj);