fix: cast indicies to std::size_t in Array

[vil02]

Description

In this PR I suggest to use std::size_t as the size of the Array. The advantage is that it avoids sign conversions and it seems to simplify the logic.
In order to avoid sign conversions I suggest to cast indices to std::size_t.

Checklist

• A description of the changes in this PR is mentioned above.
• All the new and existing tests pass.
• The code follows the code style and conventions of the project.
• No plagiarized, duplicated, or repetitive code that has been directly copied from another source.
• I have read the whole Contributing guidelines of the project and its resources/related pages.

Screenshots (if any)

Note to reviewers

Use std::size_t as the size of Array.
Cast indices to std::size_t in Array.

[mertcandav]

This changes seems not possible. Jule uses integer types for indexing types. We can use std::size_t but Jule developers can not use exact size of std::size_t. API is just interface to develop integrated C++ codes for Jule, therefore API should compatible with Jule's rules.

We should keep current implementation but also we can add alternative function overloading for std::size_t to relevant functions.

[mertcandav]

LGTM. Thanks for your contribution.