Port LuaRocks to Teal

LuaRocks is the package manager for the Lua language. It is written in pure Lua, making use of several optional libraries. The goal of this project is to port the LuaRocks source code to Teal, a statically typed language that compiles to Lua (Teal is to Lua somewhat like TypeScript is to JavaScript). Porting LuaRocks to Teal comprises essentially of writing type annotations to its source code, but will also allow for many opportunities for refactoring and improving its codebase, understanding and reporting on limitations of the Teal language and possibly inform or contribute to its development.