feat(csharp): Generate README.md

[amckinney]

Overview

This adds support for generating C# README.md files by interfacing with the generator-cli (via the CsharpGeneratorAgent type).

The following sections are generated for all README.md files:

• Installation
• Usage
• Exception Handling
• Retries (Advanced)
• Timeouts (Advanced)

Implementation

This updates the shared AbstractGeneratorAgent type so that it consolidates more of the shared logic required to produce README.md and reference.md files (e.g. reading the features.yml, producing the GitHub remote configuration, etc). The generator is expected to implement an interface that looks like the following:

export class CsharpGeneratorAgent extends AbstractGeneratorAgent<SdkGeneratorContext> {
    private readmeConfigBuilder: ReadmeConfigBuilder;

    public getReadmeConfig(
        args: AbstractGeneratorAgent.ReadmeConfigArgs<SdkGeneratorContext>
    ): FernGeneratorCli.ReadmeConfig {
        return this.readmeConfigBuilder.build({
            context: args.context,
            remote: args.remote,
            featureConfig: args.featureConfig,
            endpointSnippets: args.endpointSnippets
        });
    }

    public getLanguage(): FernGeneratorCli.Language {
        return FernGeneratorCli.Language.Csharp;
    }
}

The ReadmeConfigBuilder used here is scoped to each language, but it shares a similar structure between each implementation (i.e. it interacts with a ReadmeSnippetBuilder and produces the corresponding FernGeneratorCli.LanguageInfo).

Future improvements

There's additional functionality we can consolidate in the new AbstractReadmeSnippetBuilder.

For now, both of the language-specific implementations have their own representation of the IR's HttpEndpoint (which is extended to include a FernFilepath). Once the HttpEndpoint itself has the FernFilepath, we can easily refactor the AbstractReadmeSnippetBuilder as a generic type, and DRY up many of the helper functions (e.g. buildEndpoints, getEndpointsForFeature, etc).