Restrict usage of TypeScript reserved words as names for types

[demsullivan]

The dry-typescript compiler should throw an error if any types have names that conflict with reserved words in TypeScript.

For example, currently the following would not throw an error:

module Types
  include Dry.Types()
  extend Dry::Typescript

  ts_export any = Types::String # This should throw an error, because 'any' is a TypeScript reserved word.
end

[demsullivan]

Possible resources:

https://github.com/crissdev/is-keyword-js/blob/master/index.js
microsoft/TypeScript#2536