Add TypeScript Templates to the SDK generator

[eldadfux]

We need help adding TypeScript templates to this project to allow easy generation of a TypeScript SDK for the Appwrite server.

A full guide on how to add new language support to the Appwrite SDK generator is located here:
https://github.com/appwrite/sdk-generator/blob/master/CONTRIBUTING.md

A good starting point might be to use the NodeJS templates as a base for the TypeScript one. For type-hinting, the PHP7 SDK can be used as an example.

[eldadfux]

This is currently on freeze, anyone following this issue, can use the JS SDK with our types declaration file or the Deno SDK which is written for TS.