Implement new Concept Exercise: panic-recover

This issue describes how to implement the `panic-recover` concept exercise for the Go track.

## Getting started

The docs can be found here
- [What are Concept Exercises?](https://exercism.org/docs/building/product/concept-exercises)
- [Concept Exercises](https://exercism.org/docs/building/tracks/concept-exercises)
- [Concepts](https://exercism.org/docs/building/tracks/concepts)

Also, be aware of these general guidelines:

- [Exercism Markdown Specification](https://exercism.org/docs/building/markdown/markdown)
- [Exercism Formatting and Style Guide](https://exercism.org/docs/building/markdown/style-guide)

## Goal

The goal of this exercise is to teach the student how to work with `panic` and `recover` in Go.

## Learning objectives

- `panic` with error or other value
- `recover` a panic
- check the value type of the recover value
- `don't panic`: if, then only in `main` package to crash the program (e.g. if not all required services are reachable)
- other things that can panic: nil pointer dereference, index out of bounds, etc.
- A panic in the code is always a bug --> fix it! (don't use it as `try .. catch` alternative!)
- global panic handling in e.g. web-servers: their reason is to prevent potential bugs from crashing the entire server

## Out of scope

Nothing yet.

## Concepts

- `panic-recover`

## Prerequisites

- `defer`
- `type-assertions`

## Resources to refer to

- https://blog.golang.org/defer-panic-and-recover

## Implementing

Some function(s) that panic and the panic must be recovered in another function and turned into a proper error.

As an idea on how to teach "when not to use a panic/not to handle a panic but instead fix the bug":
Some functions could be already in the stub that panic on running the tests and the students task is to fix the problem. (they should fix the bug, not use `recover`)

## Help

If you have any questions while implementing the exercise, please post the questions as comments in this issue.