Add TSDoc annotations

This merge request adds annotations for TSDoc, a JSDoc-compatible code documentation format for TypeScript, which potentially opens the possibility of an auto-generated web documentation.

Notes

HTTP request bodies are referred to as <route description> route data to avoid the need to change the annotations each time those request bodies are modified. The need to describe those objects further is negated by the fact that almost all, if not all applications capable of viewing JSDoc annotations in a TypeScript library are capable of displaying the appropriate type and autocompleting it as needed.