Adds ToApiManifest extension method for converting an OpenAPI document to an APIManifest

[peombwa]

This PR fixes #46 by making the following changes:

• Adds an OpenApi to ApiManifest mapping doc that's implemented by the extension method.
• Adds ToApiManifest extension method for OpenApiDocument. The method will be used dependent tools to convert and OpenAPI document to an ApiManifest.
• Adds unit tests to validate the conversion.

Proposed Usage

// Convert an instance of OpenAPIDocument to an ApiManifest document.
var openApiDocument = new OpenApiStreamReader().Read(stream, out var diagnostic);
var apiManifest = openApiDocument.ToApiManifest("https://example.com/openApi.yaml", "MyApplicationName");
// or
var apiManifest = openApiDocument.ToApiManifest("https://example.com/openApi.yaml", "MyApplicationName", "GraphApi", "PubName", "[email protected]");

[zengin]

Thank you for applying suggested changes!

[baywet]

thanks for making the updates, a couple of things left.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
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94.5% Coverage
0.0% Duplication