Rest Client / Markdown generation

[pkedy]

This issue is for tracking generation of Markdown that works with the REST Client VS Code extension. It will generate test requests for roles with @service.

MVP features

• Interfaces
• Scaffolded implementation (N/A)
• Data Structures
  • Types
  • Unions
  • Alias
  • Enums
• Documentation on apexlang.io

Implementation-specific

N/A

Testing

• Output diff test