Add TypeScript ESLint rules

[danielrearden]

Rules copied from graphql-js

[codecov]

Codecov Report

Merging #278 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #278   +/-   ##
=======================================
  Coverage   99.49%   99.49%           
=======================================
  Files          19       19           
  Lines         595      595           
  Branches       38       38           
=======================================
  Hits          592      592           
  Misses          3        3           

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