Add Tools Beta Example using Typescript SDK

[lukeojones]

I've been experimenting with the Tools beta in Typescript and thought it would be useful to contribute a working example to this repo for those that are looking for non-Python examples.

The POC I've written is a basic command line tool that includes Addition, Subtraction, Division and Multiplication tools.

Is this contribution worth making? I don't think it would take too long to tidy up the code but want to make sure the Anthropic maintainers are wanting to go down this road before spending much time on it.