`number.floor` Implementation Incorrectly Categorized as Atom in EO

[yegor256]

Currently, it's an atom, but it can easily be implemented in EO.

Let's implement and remove the atom.

[rudrat0319]

@yegor256 I'd like to work on this. However, can u pls provide a lil more context.
Also, do let me know if you assign the issues for external contributions or should I just go ahead and submit a PR.

[yegor256]

@rudrat0319 just go ahead and submit a PR! If you need more context, please ask questions, we'll try to answer.