[C#] Implement new Concept Exercise: constants

[ErikSchierboom]

This issue describes how to implement the constants concept exercise for the C# track.

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.
• Rationale for v3.
• What are concept exercise and how they are structured?

Please also watch the following video:

• The Anatomy of a Concept Exercise.

Goal

The goal of this exercise is to teach the student the Concept of Constants in C#.

Learning objectives

• Know how to define const values.
• Know how to define readonly values.
• Know when to use const or readonly.

Out of scope

• readonly structs
• readonly properties
• ref readonly

Concepts

This Concepts Exercise's Concepts are:

• constants: know how to define const values; know how to define readonly values; know when to use const or readonly.

Prequisites

This Concept Exercise's prerequisites Concepts are:

• classes: know how to define fields.
• basics: know how to define variables.

Resources to refer to

Hints

• Readonly fields: how to define a readonly field.
• Constants: how to define constants.

After

• Readonly fields: how to define a readonly field.
• Constants: how to define constants.

Representer

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

Analyzer

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

Implementing

To implement this exercise, please follow these instructions.

Help

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

[mikedamay]

Can we include readonly structs and members in this exercise.

[mikedamay]

Closed by PR #1877