implement bit-manipulation concept exercise

This issue describes how to implement the `bit-manipulation` concept exercise for the C# track.

If you are a lapsed maintainer returning to the fold you might want to read [these instructions](https://github.com/exercism/v3/blob/master/languages/csharp/reference/implementing-a-concept-exercise.md) which reflect some changes to the file layout introduced at the start of November 2020.

## Getting started

**Please please please read the docs before starting.** Posting PRs without reading these docs will be a lot more frustrating for you during the review cycle, and exhaust Exercism's maintainers' time. So, before diving into the implementation, please read up on the following documents:

- [The features of v3](https://github.com/exercism/v3/blob/master/docs/concept-exercises.md).
- [Rationale for v3](https://github.com/exercism/v3/blob/master/docs/rationale-for-v3.md).
- [What are concept exercise and how they are structured?](https://github.com/exercism/v3/blob/master/docs/features-of-v3.md)

Please also watch the following video:

- [The Anatomy of a Concept Exercise](https://www.youtube.com/watch?v=gkbBqd7hPrA).

## Goal

The goal of this exercise is to teach the student how and why to use bits and bitwise operators.

## Learning objectives

- Know how and why to manipulate bits in C#

## Out of scope

## Concepts

- `bit-manipulation`

## Prerequisites

- `compound-operators`
- `integral-numbers`

Other prerequisites will depend on the story.

## Resources to refer to

### Hints

start with docs at docs.microsoft.com

### After

start with docs at docs.microsoft.com

## Representer

This exercise does not require any specific representation logic to be added to the [representer][representer].

## Analyzer

This exercise does not require any specific analyzer logic to be added to the [analyzer][analyzer].

## Implementing

To implement this exercise, please [follow these instructions](https://github.com/exercism/v3/blob/master/languages/csharp/reference/implementing-a-concept-exercise.md).

## Help

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

[analyzer]: https://github.com/exercism/csharp-analyzer
[representer]: https://github.com/exercism/csharp-representer