[Feature] Add support for arrays to `len()`

[Luna-Klatzer]

Is there an existing proposal for this?

• [X] I have searched the existing issues

This feature does not exist in the latest version

• [X] I am using the latest version

Proposal

Add support for arrays to built-in function len().

Example:

print(len([1, 2, 3])); // -> "3"

Exact behaviour / changes you want

• [ ] Add support to arrays in the built-in function len() present in the universe scope
• [ ] Add appropriate adjustments to the built-in function generation for len().

[Luna-Klatzer]

Implemented by #680.